What information do I need to have ready when creating an album?

Surprisingly little. The essentials are an album name, an event date, and ideally a location, since those are what guests see first on the album page. A short description is nice for context — a line about the event, or a note like "photos from the reception." The one decision that matters up front is your download policy: free downloads, paid downloads (and if paid, per-photo or whole-album pricing), or no downloads at all. Even that can be changed later though, so there's no reason to get stuck.