I think 14 each side of the ball, plus ST [P, K, PR, KR]. It adds a layer of strategy to it, do you go 3 extra receivers to be able to go 5 wide? Or add a FB and a 2nd TE to go jumbo? Same thing in the secondary or do you add a 2nd NT for goaline?
As for the time limit it could go quick if everyone is on and doing their picks as quickly as they can. If you are just logging on every 10-20 mins though, 32 rounds times 8 players times 20 mins a pick is 85 hours. That's not reasonable to expect someone on and around to make picks. The only way that works is if everyone has at least 640 players ranked and have some sort of auto pick based on those scores. Also not very reasonable. Not sure what the best way to do it would be but anyway you slice it, it's a big time commitment for a fun mental masterbastion exercise.