Hi @DerHof2007,
#1, I don't use it personally, but I believe yes you can.
#2 all your game artwork will work with launchbox, you just need to point it at your current collection.
#3 Possibly, launchbox does use autohotkey, but not something I use personally.
#4 Yes.
#5 Someone else will have to help you there, sorry.
#6 Launchbox is the desktop program, where you set everything up. Bigbox is the home theater environment, which is controller friendly and has all the bells and whistles you have probably seen, that's what you want on your cabinet.
Hope that helps you make a decision.
I'm sure many more knowledgeable than I will pop in here at some point. To help you out, and point out errors I made.