Question about APU vs GPU

I am currently buying components here and there to build a new semi-gaming rig desktop, and i was wondering how the new APUs would differ than getting a Phenom II x4 @3.2ghz. with a radeon hd 6790 card.

If i got the Current APU it would be the AMD A8-3850 Llano 2.9GHz 4MB L2 Cache Socket FM1 100W Quad-Core Desktop APU AD3850WNGXBOX

(i belive that is the highest end one currently released, correct if i am wrong),

and i would crossfire that with the highest card that i could

(question: would I be able to crossfire it with the 6790? i haven't been able to find any info on crossfiring with the new APUs)

My questions are: For a average gamer, what would give me the performance i need for decent/high gaming experience while giving me a decent amount of processing power (I only do a bit of Handbraking, and dvd ripping and other slightly intensive processes currently, but i dont want a weak cpu by any means).

How energy efficient is the APU i selected, and is there any better ones currently available?

Is there any info on crossfiring with the APUs?

What is more future proof?