In response to Riddle #3 I was originally going to say the Gringotts ATM may be back there, but now that I've seen the shop window...I can say that I have no idea what it could be. hmmm...it's got moving parts to it...what other shop in Harry Potter would use moving items as a display??? According to Teebin Uni talked about possibly involving this shop in the HP land, but when they talked about it apparently they did so like it would be involved on a smaller scale, which has now been revealed to be quite larger than we expected. So, the question is what shop has Uni talked about involving, then apparently scrapped, that has now magiked itself into the park?
On further inspection I have noticed the alleyway is not connected to Three Broomsticks, but is inbetween Honeydukes and another unnamed building. The only other shops that Uni has talked about but has not really gone into detail on is Zonkos's Joke Shop and Dervish and Bangs (which has been confirmed to make an appearance according to the news page on the official website). Could the display in the alley be for Zonko's or DnB (It could also just as easily be an animated display for Honeydukes), or does Teebin's Riddle have nothing to do with the window display? I bring up this other possibility because Teebin mentions the *Whatever It Is* being on the right, and the display window is clearly on the left. Maybe I was right with my first guess of Gringotts, maybe it's been turned into a walk-up interactive banking experience involving goblins and such.
(Teebin must be enjoying the chaos he's created, no offense T-Man)