Ask what their approach is to meals and feeding, to bottles, how often they take the children out, what qualufications they have, what they do if they are ill, what their attitude is to coughs and colds, how long the child needs to be away if sick, how many other children there are and of what ages.
What holidays they take and what you do about school holidays. What health and safety courses they have done. What skills your child will develop. Ask about exercise, singing, play, naps and nappies ( do you bring your own ).
Ask about insurance. About whether they take the children to nursery and or school. And fees. And a model contract .
I have the most wonderful childminders in the world. Ds wrote a superb article about them for the NCMA 17 months ago ( not even a stealth boast here, just a boast).
Get a feel for if they are fun, calm and love the children they care for.
HTH