Thanks for the questions, and great to hear that you're bringing a newbie.
Here are the answers to your questions:
Can you buy a day pass in advance?
Yes. Your friend could purchase a day pass online before May 1. Or, they could purchase a day pass on Monday of the event (that's new).
Assume the Day Pass gets him into Tour Expo, Demo Rides, and Seminars?
I did not think you needed a pass or wristband to get into the Monday Night kickoff since the official registration does on open until Tue. Only early bird wristband pick-up is on Monday is that correct?
Monday's Opening Celebration is a perk of pre-registering for Americade. Only those with a classic, premium, platinum or FWH band will be allowed to enter. Anyone who is pre-registered can pick up their registration packet starting on Monday, June 4th at the FWH Conf. Ctr our new registration headquarters!
Hope that helps and see you soon!