Sorry I was slow to arrive, but a big thank you to community members for helping out with these questions. I will state the answers just in case any confusion lingers.
#1. The entire unit is placed at once. There is no gap between the moving model finishing their movement and the placement of the remainder of the unit.
#2. Yes you may purchase additional attacks after performing a power attack.
#3. Timing dependant. Would be best to offer a specific example and I could respond to that. In general we removed many abilities that would allow for such a scenario to occur.
-Erik