Sounds like you have some good plans on the go. Did you have some specific questions?
Couple of questions:
1. How will the in cabinet speakers perform in a in wall environment? I have the wall spacing, but have not found or read anyone that has done in cabinets in in wall setting. Maybe I am barking up the wrong tree and should stick with on/in walls.
2. The room is 2,625 cubic feet, is the M60 going to be enough for this size of a room, or should I be looking at the M80?
3. I am looking at going with the VP160, is the VP180 that great of an upgrade?
4. I am looking at going with 2 HSU subs, If I move up to the M80 do you think i would need a 2nd sub in a room of that size?
