JoeViking245

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].
 

Click the stupid upside-down triangle to the right of Complete.  It'll open a dropdown menu in which contains other actually quite smart view options. Take some time to scroll through all the stupid view/filter options available to you.  When your done getting familiar with them, select the smartest one that says Platform Categories.  There you'll be able to see your "console" and "arcade" Categories.

If you used the MAME Arcade Fullset Import Wizard, there's an option to create a playlist for vertically oriented games.  If you didn't un-check that option, there'll be a playlist called Vertically Oriented Games.
If you had un-selected that option, you could re-run the Wizard.  However, if have you have curated your collection in LaunchBox, that's probably not a good option.
 
Alternately...
..and follow the steps outlined in this post.
Arrange game by Screen type? - Features - LaunchBox Community Forums
 

They look great when looking through standalone MAME and adds a little pizazz to it. 
 
Yes.  Within the Extras, the image files (at least) are all named after the ROMs filename.  So when placed into the appropriate folder, LaunchBox will associate them with their respective game(s).  The DATs and ini ("folders") files can't be used in LaunchBox without the use of third-party plugins.
The Multimedia pack does have soundtracks and videosnaps that would work the same when placed in the appropriate folder.  I'm not sure about their quality. (Not saying they might be bad. I just have no idea)
 
"Can I gain anything using those over what LaunchBox has available for Arcade Images?"
Not really.  When you download MAMEs Extras, you get everything.  Say you go to pull out just the cabinet images and place them in 'their' folder, you're putting in every single image [they have].  Whereas, when you download media from LaunchBox, you get only the images for the games you actually have.
If you have an EmuMovies account (highly recommended), the same thing goes for soundtracks and videos (get only the ones you need).
 
Images available on the LaunchBox Database (where they're downloaded from) are relatively complete for Arcade machines.  As are the videosnaps from EmuMovies.  Anything that is or may be missing, chances are, they're missing from Extras and Multimedia as well.

Follow this and just change Arcade to your NES platform.
 

LaunchBox doesn't have (and pretty sure never had) an innate YouTube scraper.  There is an older user submitted "YouTube Scraper" plugin that you would have had to manually download and install yourself.   Here's a link to the Support Page for that scraper.  But it appears to have been abandoned.  To remove it, just delete the folder/file you added to the /Plugins/ folder [while LaunchBox is not running].  
There is another user submitted YT scraper plugin call Vidsnap Scraper that is currently active.  If you're looking for one.

If you're talking about seeing them in the Main (middle) section...

Go to Tools < Options < Media < Box Front Priorities, check the box for Arcade Cabinets and then click Move Selection Up until it's at the top of the list. Click OK to save and close the Options window.
Click Image Group and select Boxes.
Moving it the top selection works nice because it won't interfere with other Platforms (as they typically won't have any Arcade Cabinet images).
 
If you're talking about wanting to see them somewhere else, please elaborate.
 

Since you have your ROMs and CHDs located in the /roms/ folder under your MAME installation:
In LaunchBox, Edit your MAME emulator.  In the Default Command-line Parameters does it have -rompath %romlocation%?  If so, remove it.

Not sure if this falls under a double entendre or an oxymoron.   
Merged          - (0.273) 76.54 GB
Non-Merged - (0.273) 141.6 GB
That is course is for the Full set(s) and you'd only be exporting some of those.  So "to save space.."?  In the end.. Probably not.  To have the export feature [more so] work in-your-favor and "Less chances of them not working and less headache"? Most likely.

That's all dependent on the core being used for that system.
 
Just looked back up at your RetroArch screenshot. For some reason Remove Quotes got checked.  Un-check that.

The error indicates something is up with your license file. Email support@unbrokensoftware.com and they can sort it out for you.

If you have the ROMs/games loaded into RPCS3 already, you can turn on the Auto-Import feature for the platform and LaunchBox will read RPCS3's virtual drive and import those games.  So in this instance, no. It doesn't matter where you store them.

View < Media < Refresh All Images

 
Alternately, you can click on one of your PS2 games then press Ctrl+A (to select all games).  Then press F5 to refresh images for selected games.

In that case, in LaunchBox, Edit the game you want to change the default version to be played when you click Play.  When editing that game, go to the Additional Apps section [for that game].  There you'll see the different versions of that game.  [Single-]click on the games' version you want to set as default.  On that same screen, click Make Default [located on the bottom right of that screen].  Click OK to save and close the edit window.  Now when you click Play, that version you selected previously and had clicked Make Default for is the version that will be launched.

Auto-Save, 'Manual'-Save and Quick-Save are separate Save States.  The Error is trying to load a Quick-Save. (vs. creating one)
Open MAME (mame.exe) and go to General Settings < Input Assignments < User Interface and look for Save State to see the assigned keys for saving and loading States.
[The default] to create a Save State is F6.  (To create a Quick-Save, it's Shift+F6.)
[The default] to load a Save State is F7. (To load a Quick-Save, it's Shift+F7.)
 
Here's the 3 different Save States

"1" is a "manual" Save State. (I believe can be a number 1 through 9 [1 through 0?].) 
"auto" and "quick" are self-explanatory.