Do a little research in advance to answer one of those questions yourself, and then send a message with that, and the rest of the questions. It takes pressure off the next person to send a message, since you've already done 1/4 of the planning, they won't feel like they're going to end up "in charge". And once one person responds, it'll flow more naturally into a conversation, as the stakes are lower for each new person joining in.

Something like, "It sounds like they don't take reservations. We wanna show up as we can, or meet up first?"