Re 1, I'd almost bet that the sandbox mode will be the "normal" way to play, or at least the one that most people end up preferring. GC2 works that way, and IIRC the underlying architecture work on this game is basically also work on the plumbing for GC3.
Re 2, I surely hope that there will be no required RTS clickety-clickety. I also hope that there is some (optional at least) way to display movement limits--a ring like you see around constructors in GC2 if free movement is available, or a hex grid if things are kept simple. I think I'd actually prefer something closer to a pretty chess board, but six-sided.
Btw, will we control tactical combat, or just watch?
If I'm remember the gossip correctly, tactical combat will be player-controlled. I'm greedy, though--I want to be able to turn that over to a really good field commander (or just an overwhelming force) if I have one so I don't have to bother with all the clicking.