How do you get the screens to show up in Maximus Arcade? It should be in the setup.
Roms don't really have versions, the MAME program does, and every once in a while when a new MAME comes out, the ROMS will have to change. What version of MAME are you using? If you use CLRMAMEpro you can audit your roms based on your MAME version, and it will tell you which Roms are bad, which ones you are missing, etc. go to
www.mameworld.info. There is a link on that page to the easyemu CLRMAMEpro tutorial.
As for where you get these files, I am not sure you can ask that on these forums. I suggest you run CLRMAMEpro and then get the files you are missing, or a new romset from the same place you got your current romset, or use the googler on your interweb machine to find stuff.