Welcome to Rabbits Online!
There are two really good threads about diet in the Nutrition & Behaviour forum:
As an example here is what my buns eat each day
(I feed this to them together, so this is for 2x buns together):
- 1/2 scoop of pellets, either in 1 or 2 servings
- Unlimited hay (fed them a mix of grass and alfalfa hay from 2-6 months, now just grass hay)
- Approx 2 cups of packed greens per day
For greens you can get a good idea from the above threads, but my bunnies favourites are cilantro, basil, and spinach.
A loft with a ramp should be good! Bunnies are fine with multi-storey cages, and it's a good idea to have a pen (or a free roam area) to let them out during the day. I only close their cage when I'm away and no one can watch them.