You want to sure she is eating plenty of hay and drinking plenty of water. This helps buns pass any hair they ingest while grooming during shedding/molting.
You can brush her just be aware they have this skin so you want to be careful using any brushes that could scratch or cut their skin.
You really don't want to get a bun wet but it is fine to wipe with a damp cloth. You can also get your hands damp and run them across her which will help remove the loose fur as well as allowing her to enjoy pets.