Sounds good to me.

1. I would do some more planning on how you are going to control heat with either fans or a chiller.

2. If you are going to start the tank from scratch I would consider a closed loop rather then powerheads.

3. You may want to re-consider using a "tall" tank for a sump unless you are going to have it on a tall stand. A 30 gal. tank may be more workable.

4. What about a refugium?