I only have 2 mechanical hard drives in raid atm. But I need to get a SSD. So 4 probably with room for another. I had a Tagan 800bz before hand. It's great to have the extra power if you need it.
Check out the new Cougar case available end of this month:
Panzer Max Full Tower Case by COUGAR - nice youtube overview:
https://www.youtube.com/watch?v=Eo7vr5nco5w
I like the way the hard drives are hidden away - as for a PSU - anything Platinum or Titanium certified 750 watt or above should last you a good while - Super Flower or EVGA would be my preference.