CPU's are rarly defective, the only real way to verify a CPU is by doing things like stress testing to verify stablity. Granted, if you install the CPU and it doesn't boot (and you have the correct BIOS) then it could be a possible CPU issue, but it could be other things as well. The CPU is always one of the last things i figure as a problem in regards to having it crap out on me, so i wouldn't worry.
In regards to overclocking your CPU safely well it's really just a matter of keeping voltages and heat in check as those will both determine a stable overclock, you generally don't have to worry about killing your CPU due to overclocking, as modern CPU's have thermal shut down abilities so that if your chip get to hot from an overclock and reaches a certain temperature it shut itself off to prevent damage.
Since you have an unlocked chip it should be rather easy to overclock as it should really just be a matter of uping the multiplier, sometimes you don't have to worry about voltages until your reach a certain speed.