1. not worth it
2. according to http://www.extreme.outervision.com/PSUEngine should be able
3. Depend on type of game you play and resolution you play your game at.
General speacking 1080P gaming on 60 FPS monitor
First Person shooter game will not bottleneck
MMO is very likely to bottleneck
Strategy game is very likely to bottleneck
The bottleneck on amd chip is due to poor single core process ability(not like intel strong in single core)
If the game engine is program to use multiple core (6 core ++) then you can hardly notice the difference
Surly intel chip will perform faster in game but not by much(pls dont compare it in low resolution) .
4. sure can oc it but i don't think it can reach 5 ghz stable