Can I ask a sitter a question before booking? If so, how?

Definitely! In fact, as a sitter I prefer when people ask me their questions first so that I can immediately know what exactly they need.

Most people submit a request that includes the stay date(s) and it will allow you to send a message with that request where you can ask any questions you have. It doesn't go through as a final booking unless you approve it, so if you end up not liking the sitter you can just delete it and move on. I personally NEVER officially accept a booking until after a meet and greet, that's where you get to meet the sitter and ask any and every question you can think of.

I would also highly encourage you, if you haven't already, to make sure your profile is as detailed as possible. List all your pets, their likes, dislikes, feeding schedule and anything else that's important to them being happy. That really helps us sitters know if we are able to meet your pets needs without having to waste either of our time waiting for message responses.