Yes the buildings are 15mm. I just came across them and put them out for some reason. I think of them as big hangars or factory spaces. I pass the Disney studio where they are filming the Krypton TV series every morning on my way to work and you should see the size of it, and the doors.
Yes my friend seemed to really enjoy the game. You always wonder if people are just being polite but he was keen to continue the game for longer than I imagined anyone would want to on a first game and wanted to arrange a return match. Plenty of laughs and the body language was good so I am pretty sure he did enjoy it.
I actually get really nervous demoing a game now. If to fellow gamers you know you have one chance to make an impression and get them to play your choice of game again. Demoing to someone with no knowledge of figure gaming was even more nerve racking. Amazing what is obvious as a gamer but needs explaining to someone playing for the first time. Like measuring movement needs to be done from the same point on any model.