I'm at Minnesota and welcome your questions via PM. It's my first year in the program, so I might not be able to answer every question, but I'll do my best to do so.
Congrats to you and Matt Dander! I also received an offer. Like you, I'm surprised by the narrow decision window. I'm trying to plan a visit before the deadline. Hopefully I can make it happen.
I don't know if McGill or UC Santa Barbara have theory folks on wait-lists, but I declined their respective offers over the past couple of days. Hope this helps other deserving candidates.