I do like the idea of simultaneous movement florrat. It reminds me of Diplomacy, which is like my favorite game ever. I have a couple counter-comments though:
--If everybody is moving once per move cycle, do we have to wait for everybody? It might slow down the game even more. There would have to be a fair amount of time to give everyone a chance to move.
--I see that you say that movement would be done on a first come, first serve basis...if two players tried to move into the same vacant square for example, the person who posted first would succeed, and the second person's attempt would be invalid. This is fine...but it also rewards compulsively checking f.ds, which may or may not be a fun thing to do.
The alternative is something like Diplomacy, with a simultaneous resolution system...but that gets to be complicated, you need secrets and moderators, and again you'd have to wait for everyone.
Treasure chest sounds like a fine idea to me. I'll add the bit about not changing amount of IPs, thanks.