Michael, your plan seems completely workable.
As I understand your layout diagram, you want to run as many as 4 trains independently. Your power plan should do that, easily. As the guys have advised, be sure to make sure your transformers are phased correctly. If not, you'll notice a stall when your trains cross into a different power block. Just take the transformer plug out of the socket and reverse it.
Also, as RTR12 mentioned, the 180 bricks don't have handles that will allow you to adjust speed/power. This will definitely affect your running conventional engines. You seem to be aware of the circuit protection that should be utilized to protect the electronics.
Keep us posted.
Jerry
