hi guys im kinda new to all these OC stuffs n need some help here

im running Q6600 with HYPER 212 here, and OCed to 3.0Ghz
Vcore idle shown with CPUZ is 1.36 and temp is 48 C
and while stress testing it drops to around 1.32 and the hottest core's temp is around 58 C

is the vcore and temp within the safe range for Q6600? if im planning to run 24/7 ?

what apparent performance improvements we can see from overclocking the CPU to higher speed?
will this shorten the cpu lifespan?

OC just wanna try it out n see wht's the difference

but can anyone tell me is there any difference?
and the voltage of 1.36 is perfectly fine?

what benefits we get from oc our CPU?