JoeViking245

Using Custom platform icon images is not available in the free version.
If you decide to get a premium license, then it's simply a matter of placing the image files in your /LaunchBox/Images/Platform Icons/Platforms/ folder.
i.e.
DREAMM.png Installed eXoDOS Games.png ScummVM SVN.png

When launching a MAME game from LaunchBox, I can't say I've ever heard of it only opening the MAME UI. Unless of course when you right-click a game and select Open MAME. Usually if there's an issue, you'd see a flicker of a black screen, then it goes right back to LaunchBox.
The only thing I can think of that may be the issue is the ROMs being in the root of the drive (vs in a folder), in conjunction with using the -rompath parameter to tell MAME where the ROMs are located.  Not that using the parameter is bad. It's it pointing to a root drive instead of a folder.
As a test, could you put a rom into a folder, change the games path in LaunchBox to this [test] location and try launching it?
I always use 1942 (1942.zip) because it's near the top and easy to find.    So maybe try something like D:\games\1942.zip and see if that launches correctly.
 
EDIT:  Just did some testing and appears MAME doesn't like (or doesn't know how) looking in a root drive for ROMs.  aka, you need to place the ROMs into a folder.
You can create the folder name of your choosing and move the ROMs there.  Then in LaunchBox, in the Arcade platform, select a game then press Ctrl+A to select all games.  Then go to Tools < File Management < Change ROMs Folder Path for Selected Games... and point to the new folder they're in.

What you're seeing is actually an empty 3D Model (vs a 3D Image).  The Models get composed from Box-Front, Box-Back and Spine (or Clear Logo) images.
They actually look quite nice if you have those images available.
You can disable the "hideous" 3D Model image under Tools < Options < Visuals < Game Details - Show 3D Model.

Select the games in the given platform and then go to:
Tools < File Management < Change ROMs Folder Path for Selected Games...

Try updating your local database file.    Tools < Download < Force Update Games Database Metadata...
BTW, I have never heard a solution to any issue being "delete LaunchBox and reinstall it entirely".  

I just ran a test to confirm what you're experiencing.
Tools < Import < ROM Files < Single Platform
In my case I selected a folder "Nintendo 64".  It auto-detected the platform and then gave the option to install RetroArch. Choosing "Install RetroArch", the wizard proceeds without giving the option to download bezels.
 
Test #2, same steps but instead of having LaunchBox automatically install the emulator, I selected "Manually Configure Emulator".  Added a new emulator (RetroArch) and continuing through the wizard, the "Download Bezels from The Bezel Project?" screen appeared this time.
 
My guess as to what's happening is, when choosing "Install RetroArch", RetroArch isn't technically installed until the end of the Import process. So the wizard doesn't "see" retroarch,.exe and skips the bezel section.
 
The good thing is, it'll only do that once. Or at least until RetroArch exists as an emulator.  The bad thing is it happens once. 
The easy fix is to re-add those games and the wizard this time should show the bezel option screen.  Subsequent platforms using RetroArch as the emulator should see the bezel option screen during the import wizard as well.
Feel free to report a bug here:  Feedback - LaunchBox  This way the developers will have a 1st hand report of the bug and can process accordingly. (Rather than them sifting through oodles of Forum threads.)

Before you indicated is said Nothing to Do.  No Missing Playlists makes more sense.   I just ran a test on v13.18 and v13.19 and it worked here to 'add the missing playlist'. 
Based on the actual message it gave to you, makes me wonder, if you switched to the Playlists view (left panel, change from Platform Category to Playlists), if it would appear there.  And that for some reason it just didn't nest it under the platform.  Maybe look there to see if there're 2 [similar] playlists (the 1 generated and the one you created).
 
The one it generated for me looks like this.

Those are some of the files that are supposed to be inside sf2.zip.  Since this is the parent ROM for the game, this (plus several others) should all be inside the zip file.
Beyond that, not sure what to tell you. 

Your 1st screenshot is showing (not showing) the games' Clear Logos.  If a game doesn't have its Clear Log, plain text will be shown.
If in LaunchBox, you recently added [more] game Clear Logos (or any other images for that matter), in BigBox you need to update the image cache.
System Menu < Options < Image Cache - select 1 or more options
 
Your 2nd screenshot if for Platform Videos.

I presume "EmuMovies".  
After adding your EmuMovies credentials into LaunchBox and verifying it works (which you have done).. I think what you're after is
Tools Download Update Metadata and Media for All Games When you get to the LaunchBox images click Check None  Then for the EmuMovies click Check All (or just the ones you actually need)

LaunchBox is meant to be a keyboard and mouse application. 
Sounds like maybe the buttons are Keyboard Input (vs XInput).  A good way to tell is open notepad and press player1-button-5.  Does a "z" get typed?  If it does, also try this... (this assumes you have a Pause button...) Select a game.  Press and hold player1-button-1 and press Pause.  If all goes well, you just "pressed Ctrl+P" and the game should start.
This may not be ideal.  But again, it's intended to be a keyboard and mouse application. 

When clicking it (one or the other of the red arrows) it should open a dropdown menu (red box) to select from.  You then can scroll down to Platform Category (or Platform or Playlist or whatever you wish)

The issue I believe with TeknoParrot is, is that it's actually a launcher for the games.  So when you launch the "game", it then launches the "actual game" and quits itself.  LaunchBox sees the "game" is no longer 'running' (even though the "actual game" is still loading) and sees no reason to keep the loading screen up, thus closing it.  So even if you set the loading time to 20 minutes, it's going to close virtually right-away.
 
TeknoParrot (and also Steam for that matter) aside and keeping with this threads Title:
You can set it per game or per emulator for up to 30 seconds.
Per game:  Edit the game and in the Startup/Pause section, check Override Default Startup Screen Settings then click Customize.  Check Enable and adjust the slider as necessary.
Per Emulator:  Edit the emulator and in the Startup Screen section, adjust the slider as necessary.
Per many games:  Select the games you want to adjust it for.  Press Ctrl+E to start the Bulk Edit Wizard.  For the Field, select Startup Screen - Load Delay.  For the Value, adjust the slider as necessary.  Follow the prompts to save.
 
If 30 seconds still isn't enough, there's a plugin for that.  But it can only go to a max of 5 minutes.
 

With LaunchBox Premium, you can add an image to \LaunchBox\Images\Platform Icons\.
From there, go to the subfolder for which image type it is.  Platform Categories, Platforms (in your case) or Playlists.
Put your image in 'there' and name it exactly the same as the Category/Platform/Playlist. 
i.e.  D:\LaunchBox\Images\Platform Icons\Platforms\Windows Classic.png

It's probably not 'hanging'.  It's probably just doesn't have focus.
Edit MAME (in LB) and un-check "Attempt to hide console window on startup/shutdown"

It's listed outside the Consoles category and inside it. Just like how the checkboxes are checked. 
Un-check Root to have it be listed only inside the Console category.

K. That makes sense now.  In BigBox, System Menu, Options, Controller Mappings.  Map a button (or button combo) to Close the Active Window.  (NOT "Exit".  That exits BigBox.)  Use the button (or combo. whatever you assigned) when in-game, to exit the game and return to BigBox.
 
No.  Keyboard mode means the buttons and joy movements on the control panel are actually sending key presses.   i.e.  If I had notepad opened and moved player 2's joystick up, down, left then right... it would type out "rfdg".  That's the default MAME mapping for that joystick.

I believe what you did was edit the platform(s) and the (re)set the Folder Path for "Game".  When you add new games to that folder, that's when it will find new games.
To change the path for existing games, in LaunchBox, select all the games in a given platform ("system").  Then go to Tools < File Management - Change ROMs Folder Path for Selected Games...

Yes.  For the MAME emulator, just add a new emulator and point it to your mame.exe file.
For the ROMs, that's a little tricky, but it can be done.
For some [valid, I'm sure] reason, Ludlow saves the ROMs into folders named after each games ROM archive name.
So, to add one of those games to LaunchBox, in your Arcade platform,
Press Ctrl+N to manually add a file Give the game its Title Go to the Launching section Under ROM File, type or paste in the path to the "roms" folder then add a forward slash and type in the name of the games folder i.e.   D:\MAME-AO\0274\roms\flagrall Click OK to save and close wash, rinse and repeat for other games For the emulator's Command-line Parameters, you will need to add in -rompath %romlocation%.
 
As for automagically importing all the games, you won't be able to do that with way he had saved them.  To import, LaunchBox looks for files (vs folders).  And specifically for MAME/Arcade, it looks for .zip or .7z files.  You'd get to get more creative than what I mentioned above to be able to LaunchBox's Bulk Import Tools.

You need to un-check Auto-Populate to be able to manually add games to a playlist.
[If it helps] you can start with - creating the playlist using the Auto-Populate checkbox and filter(s).  Click Games to see the games that fit that filter. Go back to Auto-Populate, and un-check the box.  Click OK to save and Close.

Edit your UMK3+ game in LaunchBox.  Can you share a screenshot of the Launching section and also one of the Emulation section?

Depending on how you imported them, Super Nintendo Entertainment System (SNES) is typically a Platform.  SNES would then fall under the Category 'Consoles'.
What I think you're wanting (needing) to do is have your Famicom games into their own Platform.
If you can somehow manage to select just those games in your SNES platform, you can press Ctrl+E to start the bulk edit wizard.  Follow the prompts and then select to change the Platform and type in the new Platform name ("Famicom" or whatever you choose).
Alternately, remove all the SNES games and then reimport the [actual] SNES games and Famicom games separately into their own respective Platform.

The running scripts are only available as along as the 'emulator' (batch file, in your case) is running.  So if the batch file only Starts the process without the /wait parameter, it exits after the executing the Start command. Thus abandoning the Running Script.
So depending on what's in your batch file might be why none of the attempts are working.

Arcade machines weren't delivered in boxes.  They typically used wooden crates.  With that, you won't find [true] 'Box Front' images.  If anything, there should only be 'Fanart Box Fronts'.
For the Arcade platform, most people use 'Advertisement Flyers - Front' images.  Myself, I use 'Arcade Cabinet' images.  Neither of those are checked by default.

OK, so it's only closing BigBox.  That makes more sense.  
In BigBox, go to the System Menu < Options - Keyboard Mappings.  Look for the mapping for Exit and select it.  It should have an "X" next to it.  Press Enter on your keyboard and wait 5 seconds to clear it completely.
Alternately, while waiting the 5 seconds, you can press a different key to map as Exit [BigBox].