It should be enough,but you cant overclock on it.
I would still get an aftermarket heat sink,like a Cooler Master Hyper 212 EVO.
About applying Thermal Paste,you just need to put a pea-sized drop in the middle if the CPU,put the heat sink on top,screw everytihng in place and you're done.
If I did that on my first try,you have nothing to worry about it.
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