Will 7950 have tearing performance along with my this rig?

[cool.dx.rip]

Guys,I have a 18.5inch led monitor.
My config is:
PRO:i5 3470
Ram:8gb ddr3 1333
PSU:550watt (coolermaster or corsair){not decide}
MOBO:gigabyte b75 d3v
1)I am planning to buy 7950.a tech frnd told me that if i buy it will give me tearing performace cause i have 1366*768 RES. with 60 fps or hz.so the gpu will send more fps than needed that time.it will destroy gaming experience.is it true?he advice me to get 7850 2gb.
2)what if i set it 75hz?will still do prob?
3)Does powerful gpu more future proof?for example if 7850 protects 3 years of playing game smoothly than 7950 will protect 5 yrs,7990 will protects 7-8 years.M i right?
ABOUT ME:M a casual and normal gamer so not much hardcore about what i got in performance.i just want to play game smmothly that's it and want my gpu long run in future.one time investment.
N:B: Sorry 4 my BAD ENGLISH.