M.G.
I think "why are you doing childcare?" is a really open ended question. It leads to how a person got into caring for children and may give you a little insight into the providers personality. Turn the tables around a little and ask "what do you think the most important things are to look for in a provider", the answers would give you insight as to that providers care.
I love that you are looking for questions. I absolutly hate it when people come to interview me and have no idea of what they should ask me!!
M