First of all, when determining what size cage to get, you should ask yourself, will she be spending the majority of her time in the cage? or the majority of her time out and about the house with you when you're home??
If she's going to have to stay in the cage most of the time, then you should get something that's quite big. Alot of rabbit owners find that the Cubes and Coroplast (C&C) cages
that are used for guinea pigs are the best, because you can make them as big as you like.
If she's going to be a house rabbit with free range while you're at home, then you should have a cage that is a minimum
size of 2 square feet per pound that she weighs. Thus, a 2' by 3' cage would probably be best.
It's been my experience that water bowls (unless the kind that can be attached to the cage), are easily tipped over, and most people will agree that rabbits shouldn't get wet. They are very susceptible to respriatory illnesses like Pasturella. Thus, if they get wet, and don't dry quickly enough or properly, they can get quite sick.
It's easier to monitor how much water your rabbit is drinking when they're drinking from a bottle. One of the first signs that a rabbit is sick will be the amount of water or food they are drinking and eating (or more importantly, not eating). Rabbits will stop eating or drinking when things go wrong.
I can't think of anything else that is a necessity for a rabbit's cage. Unless you're thinking of litter box training her, in which case you will want that in there, and you'll want to make sure that there's enough space in the cage for that, too.