From GT3 Website
The race length will be between 2 to 5 hours long. Driver Swapping is mandatory at 1 for 2 hour events and 2 for an event longer than 2 hours, minimum drivers on team requirement is 3, there is no maximum.
So you must swap once for 2 hour events 2 for 2+ hours
There is no mention of Safety Car on your website. It just says wait for admin instructions if you can't make it back to the pits.
I suggest you a) produce a proper calendar and post it here b) make a proper rules thread with all the info that we've asked about, and order it correctly, I don't care what points we get or what colour the pace car is but I do care about important race stuff like SCs, quali, and other stuff. I'm sure you can look around at other series and see how their rules are done.
It is organized, the rules just need to be clarified and the schedule seems to be fine IMO, he just added 2 more events. There's a suggestions thread, btw.
Can we change of car model during the season(I hope not, but as it isn't stated in the rules, I prefer to ask)? If yes, do we get any penalty for doing so?