1. Heat spreader increases overclocking potential, if you are going to overclock memory components, i'd recomend them.
Otherwise, there's no use of a heatspreader other than make your ram look pretty.
I must warn you, that RAM overclocking is nearby useless in performance terms.
2.
Phenom II is an excellent choice, even through some people despise.
If your tendency is to run all games above 40 fps, choose Phenom II
If you tendency is maximize fps, core i5 2500K.
AMD has a much better cost benefit, but Intel is more powerful in terms of perfomance.
I have a Phenom II X6 1055T, and i'm very satisfied with it's performance.
So, none of them are the best, they both have benefits and drawbacks. Choose Intel if you want true performance or AMD if you want less performance with less cost.
Take your conclusions here
Performance comparison: X4 965 VS 2500K3.
Both of them are good, but GTX 560 Ti is 6% faster, consumes less power and has a higher pixel rate.
So, choose GTX 560 Ti.
4. Choose SATA 3, because it's transfer speed is doubled compared to SATA 2.
WARNING: choosing SATA 3 means you must install windows vista or 7, due to 64mb cache.