From my
experience a 30 X 36 in cage will house one breeding doe and an average litter (8 kits) up to the age of eight weeks. After eight weeks the kits should either be butchered or housed in a "grow out" cage so that the doe can start prepping for her next litter. It really get's cramped in there pretty fast. Does can get pretty territorial once they are pregnant so I wouldn't house them together... for the sake of the children

One doe with eight kits pretty much fills a 30x36 so there's really no way of getting more than one doe comfortable in a cage that size with all the kits.
Young females can be housed together until you intend to breed them, then they will need their own cage. Young males will start fighting after about 12 weeks old. They will bite each others genitals and can maim each other, so if you intend to raise a new buck for breeding, then get him his own cage too.
If you're raising for meat then I suspect you'll want to keep the does bred and producing kits at a reasonable rate. Here's how I do it:
I try to keep 4 does and one buck. I try to breed them so that two does are due to kindle on the same day. This way if one has any trouble I can foster kits from one doe to the other. This comes in handy when one doe kindles 12 kits and the other only kindles 4. I can even out the litters so that the does have an easier time and the kits all get to eat well.
I like to keep kindlings spaced by two weeks, so two does kindle today and the other two does kindle two weeks from now. This gives the buck two weeks between "breeding weekends" to ensure high fertility. This also means that I only have to butcher 16 rabbits at a time and I get a two week break between "Freezer Camp" orientations.
When it comes to re-breeding I usually try to get that done when the does current litter is six weeks old. Does are more receptive to a buck when they still have a litter around for some reason. This gives the doe two weeks more with the current kits before they ween, then she get's two weeks off (without kits) to dry up and get ready for the next litter. I've heard of people re-breeding earlier but I've not been too keen to push my does that hard.
I hope that helps a little bit.
Good luck