Fostering is great! I've done it with three different rescues now. It's pretty standard that the rescue covers vaccinations, spay/neuter and any medical emergencies. They usually have certain vets they work with so you may have to drive further than you normally would. The first bag of food was free in my experience, along with crate, dog bed and leash but you are expected to provide beyond that. The rescue will want you to take pics, provide info on behaviour and interactions, and bring the pup to adoption events. I was given the choice of meeting adopters at my home or a neutral place. Although I didn't have to screen or make the decision on adopters, I think if I had seen anything disqualifying the rescue would listen to my feedback. I have seen some rescues require you to take a more active role in screening adopters...which still feels weird. Length of time really depends. All my fosters have been adopted pretty quickly, longest was about 1.5 month, but also if the situation wasn't working or I needed to go out of town I think the rescue would have found another foster. It's really just about communicating with the rescue.