It sounds like Buster is curious and wants to get close and check her out, but he is too nervous to. So where better to get a good look at her, then from the top of his cage, haha.
Lots of hay is great for a new bunny, but she will need either pellets and/or veggies in her diet so that she is getting the proper nutrition. Is it that you have offered her pellets and she just isn't eating them, or you haven't started her on pellets yet? Which ever you do, it's good to introduce all new foods gradually, and one at a time. The exception is grass hay. That doesn't usually cause digestive upset with sudden introduction into the diet, unless it is a grain hay with grain in it. For the pellets, you just do it like when you are transitioning from one pellet to the other, except you don't have old pellets to transition off of.
Lots of hay is great for a new bunny, but she will need either pellets and/or veggies in her diet so that she is getting the proper nutrition. Is it that you have offered her pellets and she just isn't eating them, or you haven't started her on pellets yet? Which ever you do, it's good to introduce all new foods gradually, and one at a time. The exception is grass hay. That doesn't usually cause digestive upset with sudden introduction into the diet, unless it is a grain hay with grain in it. For the pellets, you just do it like when you are transitioning from one pellet to the other, except you don't have old pellets to transition off of.