The most important thing is that babies shouldn’t leave their mums until they’re 8 weeks old
I’m sure you’ve done lots of research, but bunnies need much more space than most people think! Lots of people here don’t keep their rabbits in a cage at all, but if you do have a cage, make sure it has a pen or run attached so they’re never confined to a tiny space.
When you first bring her home, keep her diet simple, just grass hay and alfalfa based pellets (If she comes with pellets from the breeder, slowly switch her over to the new ones over the course of a week or two by mixing them 25/75, 50/50, then 75/25). You can also feed young buns alfalfa hay if you prefer, but they can’t eat it as adults and need to be weaned off it, which can be tricky sometimes. If they have alfalfa based pellets, its not essential to have alfalfa hay too.
You can introduce veggies at 12 weeks, again slowly, one type of veg at a time in small pieces and gradually increasing.
She might be shy at first, so let her come to you, and don’t overwhelm her with attention
Spays are generally at 6 months, and neuters can be earlier provided testicles have dropped and the bun is big enough
The BUNNY INFO section has lots of useful information on safe types of veg, litter training your new bun, and building a suitable habitat 