Hi all, not a noob, but my questions may very well be :-D

1) I used Arpicade ver 3 at first, and found it easy to get into the system menu where you shut down etc. How do you access it on ver 5 ?

2) Except the given folders like daphne and mame - can anyone tell which roms go in which folder, like model 2/3 and naomi? I've tried googling
    but I didn't get a answer I understood. A list would be helpful

3) Has someone else noticed that when you try to start a game and it shuts down back to the game selection - when you try the exact game again -
it works!? At first I thought it was the wrong rom-set, but when I accidentally tried one game again I found it to be working. Is this a known bug or am
I doing something wrong?

4) How do you get the old classic game Timber to work? I've tried every rom and emulator available - but alas nothing works :-(

Thanks for your patience and I hope to get at least some answers 

It should be 'f4' or 'service' to access the service menu.  Were you on an old version of ARpiCADE_3?   I think it was the same on the later 3 releases.

SEGA Model 2 games go in the model 2 folder - emulator was formally called 'Nebula'
SEGA Model 3 games go in the 3 folder -  emulator is called 'Supermodel'
SEGA Naomi and Sammy Atomiswave games go in the Naomi folder - emulator is 'Flycast'
- each uses MAME roms but I'm not sure from which MAME version... best bet is to either search for specific sets for that emulator or try MAME romsets you already have and hope they work.

3. that's a known bug.  You may want to increase your 5v slightly from what you had with the Pi3, it seems this happens more when the 5v is a bit low.

4. as far as I know it should work fine GMAME0.275 but I'll have to load it up to be sure.  I'll check this out today.