Wow. Great thread, and good luck! I will be following along closely as this is my long term plan as well with my rf7ii rc64 combo once I can save up do up a new room. I think you're on the right track. I'm a total newbie but everywhere I've read says that 4 speakers up top make a big difference over just two.
Placements look good to me, and adding that extra wiring in the back for future sub relocations is definitely a necessity.
Good luck !