There will be a calendar either when you check in, or in the room. If you don't have one, be sure to ask for one. I don't think the events in the gift shop are listed in that calendar, but there is usually a sign at the front of the gift shop that says what special things are happening that week. Heads up, there was an extra fee for the animal figure paintings. I don't remember what it was, as we didn't do it, but I remember thinking it was reasonable. We would have done it, but the timing just didn't work out.
Here is a link to Buzz's twitter page with a picture of the May recreation calendar:
May Recreation Editing to add: I just took a closer look at the rec calendar and saw that it was mostly pool activities....but...I'm guessing there will still be a rec calendar during the pool closure though I don't know what types of rec it will include. It's possible they move some games elsewhere on the grounds. That's a hypothesis.
Your son who loves construction will probably have a great time watching the tower work. One perk to stopping by the front desk at check- in, was that our kids received bags with coloring books, crayons, stickers, and a card with a penny attached for making a wish in the fountain. We did find the main building to be rather calm overall compared to other resorts we've been to and that was over spring break. There is a small tv with a few chairs near the check-in desks that plays cartoons throughout the day. We chilled there for a little bit on arrival morning.
I’ve heard of some buses being completely full or standing room only at some stops. 
