To answer the questions.

You will need a power supply with a 6 in pcie
You will need a Higher end CPU cooler or GPU cooler.

I have been having very good luck with the dual antec kuhler shelf setup. This also makes a nice stand for the card. I have also been having very very good results with the corsair H60.

The cards HAVE to have a backplate,or they will have trouble booting (blinking or solid lights).

The boards will still connect but not hash in this state. It is poor contact or poor cooling (same thing).

The boards flex easily and even if you can not see it, it will   make your board
1. Not boot, blink
2. Boot , throw a high hash rate but all errors
3. Hash slowly.