Every rescue is different and all agreements within that rescue and different fosterers will be different.
The rescue I am involved with some foster homes provide their own hutches, whereas other foster homes have them provided for them. Some foster homes provide their own hay and pellets others have may have hay and / or A&P pellets provided. Vet bills are covered by ARC. Everyone provides their own vegetables and time and transportation to the vets.
Youare best to contact what ever rescue you are considering fostering for.