1) Its not an unlocked processor so you're not going to really be able to overclock it, not to the same degree as an unlocked processor. At most it will only overclock a few hundred MHz. So if it runs at 3.2 GHz stock it might only over clock to 3.4 or 3.5 compared to an I5 2500k that can overclock to 4.5 GHz.
2) 67 degrees is pretty high IMO. I would get an aftermarket fan/heatsink even for minor overclocking.