BuddyPress.org

For the life of me I cannot find how to do the two things I need to do. I think I can figure it out if I knew where the templates for the custom fields are at but I can’t find them. I am trying to do the following:
1) For the datepicker, only allow the year to be 18 years ago, meaning 18 and older signups.
2) I also need to create a custom fields that is a type ahead of all of the (large) airports in the US so that users can only select from those airports, a dropdown would take too long to input the data, and be to hard for users to use. I can get a csv I am sure or even just raw html, whatever. I am a theme/plugin developer so I know my way around, just can’t find the right files.

Any help on this would be greatly appreciated. Thank you guys.