For a toilet for that many, consider Walmart's portable potty (Camco?). It's easy to dump at any state campground on the way out or at home in your toilet if you have a strong stomach. Nothing wrong with a cathole, this just saves time if you have to deal with that many people. (Or it's late season - I personally hate digging in frozen ground.) Surface pooping is illegal for very good reasons. If you want a cheaper option that works just as well, a 5 gallon bucket with a seat-lid (they're like $20) is an easy way to go, just throw a contractor trash bag in with an inch of kitty litter, and throw a bit more in after each use. You can just throw that out in a dumpster, no fuss.
For cooking our group takes turns - one guy cooks and another does KP in rotation each night. We keep water usage low not for conservation but just because it's easier cleanup - if you focus on oil/fat-based cooking e.g. cast iron skillets and griddles you can usually just wipe them clean with a few paper towels and be good to go for the next morning.
We share food, too. We're a member of a local meat CSA so I'll usually bring T-bones for one night, one guy does gumbo, etc. It's tradition that the night before the opener, at least one person will bring some elk from the year before. Nothing like starting a hunt with the taste of what you're after fresh in your mind... We don't share breakfast. This isn't a hotel and we're all usually moving out at like 4am so we just do granola bars or whatever each person wants.
We also rotate other camp chores. About halfway through a week-long trip, one guy will drive to town for supplies. We can easily bring in everything we need, but it's less stressful if we just assume one trip will be done - no agonizing over bringing a ton of extra crap in case a pair of boots springs a leak or a tent pole says "this is my last year." It also stops us from having every guy bringing two massive coolers full of ice, some of which will be wasted money/effort. We usually only have 1-2 guys fill their coolers with ice, and that's enough to pack out 3-4 elk. If we're getting lucky, we can get more on the town trip.
YMMV but where we go we don't bring firewood. Even the kiln-dried stuff. I've never seen this anywhere else, but where we go the USFS will drop trees near the road and parking area as part of their yearly maintenance, and they encourage folks to buck up and use that instead of bringing their own wood. It's pretty smart. Folks on a budget would have cut their own stuff anyway, and this way they can control folks bringing in insect-ridden junk AND control what people end up burning. Some monkey from out of state is always going to try to chop down and burn an aspen and smoke out the whole campground, so this cuts down on that.
For everything else folks are on their own. We help each other with pack-outs (for a meat share) but other than the above, we hunt (and live) independently.