On behalf of Team 811, welcome to the FIRST community!!
Good rules! School should come before FIRST. Safety is critical!! My brother actually had a bad accident because our safty regulations were not respected as well as they should have been. As for the hours dedication, I've personally gone on record for 8 days, 9 hours of time purely spent at our FIRST BASE!!! I hope you have members as crazy as I am, but obviously not everyone wants to/can do this! I'd say time measurements are good for general records, but if someone cannot come as often as they'd like, but they're productive for the time they do attend, and they're a significant member of the team, they should not be penalized because they could not make it as often as others, especially if these others are not as productive as they are.
This is a link to our team's Manual... it's 5-6? years in the making, and it contains basically EVERYTHING! take a look, use it as a reference if you want!
http://www.team811.com/files/download.php?id=5
Also, something else that Team 811 does is it has a Declaration of Membership... basically this is a formal document listing all the team goals and rules, and everyone signs this sheet, stating that they intend to follow and respect these rules to the best of their ability... this really gives perspective to the whole "team" environment. Sorry I dont have a link for this! but feel free to take a look around our site in general!
http://www.team811.com/index.php
Good Luck!!!