I use a dog boarding service similar to what you want to do. She is a member of
http://www.nards.co.uk/ and they also have a contract that she has adapted for her own use as well. She also has a check list type questionnaire that you have to fill out, with commands dog knows, any issues, any 'no go' areas, ie some dogs will not have their paws touched. Normal routine, times of feeding etc.
If my dog is on any meds (hes on optimmune for dry eye) then I have to sign a seperate form with times/quantities and a permission signature. Regarding vets, if its an emergency then she will take my dog to my own vets if possible (its a vet hospital and only around 3 miles away) and ring me from the vets, I would expect to pay over the telephone if I was on holiday or arrange with the vets myself when I got back. I certainly wouldnt expect them to pay the vets bills (also I would imagine that she would be able to get hold of me within the time my dog was being treated).
She has a lovely house, and also facilities to seperate her own dogs should she need to.