Hermits can kill each other, I wouldn't be worried about that!
The frogspawn should be fine anywhere in the tank with that much light, so I wouldn't worry too much about placement other than factoring in the flow. I would start running the light at 6 hours, and each week go up one hour until you hit 8. The only time I have ever had to acclimate corals were when they were in bad lighting conditions and went into REALLY powerful lights. 150w halides are pretty standard and should be fine over that sized tank. Let them shine!