well welcome to the board but dude alot of those questions can be answered with a little research on your part--besides the best place for j-pac info is the ultimarc site, it gives hook up instructions and usage there. BUT because I'm a swell guy and its a slow day, here goes:
1. Arcadeos is a DOS based front end--mame is the executable--they are 2 different things--generally with arcadeos your run dmame (dos mame)
2. it might be-never had one--best cards for mame are the arcadevga by ultimarc, trident t64, some ATI's and some nvidia--others may pipe in about their cards--I've only used the trident and it works very well with advmame.
3. no--it takes some configuration, a little patience and a blood sacrifice to pac-man (goats blood will do)
4.yes they jamma interface can handle the coin mechs--if properly connected
5. see question 1
6.yes--arcadeos and mamewah are the two best front ends for keyboardless mameing in my humble opinion
7.no but its easier--the trident and other pc cards require a set up process
8.pc monitor or arcade monitor? both run well with mame but are completely different setups.