I have an idea for a theme for a game, and have a couple thoughts on some of the mechanics as well. However, I've never run a game before, so there are questions I will inevitably have along the way.
Are any of our humble GMs willing to be pestered by some PMs over the next couple weeks or months as I work on this, and to serve as a sort of sounding board? I don't know if it would preclude them from playing in the game – I assume that it will, as I'm sure I'll be asking specific questions that might give them more insight into the game than a standard player would have – but I would greatly appreciate the assistance. Having someone else to talk to about it along the way might also spur me on to make sure I finish it, too.

The idea is "Football/Soccer Mafia," where the "town" is a team where some members are actually trying to destroy the club from the inside, for reasons I have yet to make up.
As such, the obvious number of players would be 11, but I was also thinking it could be for 12. My first question, in either case, is what is a good balance of town/scum at those numbers? Are there any good articles somewhere on the internets that talk about the basics of game construction and would cover this topic?
I appreciate any info/input, and also if this theme has already been done, please let me know so I don't get halfway down the rabbit hole just to discover I'm late to the party!