I think it's totally fine to do it via email! It's certainly a cheaper alternative. I know for me sometimes I prefer things in email because I tend to lose things that come in the mail. If it's in email they'll always have it to go back to. But it's also really fun to get things in the mail, especially for something exciting like a wedding.
If you are going to do it in an email, I would send the 2 emails separately (i.e. send the one asking for information now, and then a month from now send the pre-travel brochure). If you make the pre-travel brochure separate I think you can make it more of a fun email.