overclocking dosent directly affect the lifespan of parts, its the heat produced by the raised clock, looking through this it looks like your buying a 3rd party cooler... well it dosent look to be the worst
as for overclocking, well it would appear that you have one of asus's overclocking utility's which will basicly hold your hand while overclocking, or if you like i3 i5 and i7 processors have turbo boost ... since i do not have this board, i cant tell you where to find this but i hope this helps
Stay under Intel's voltage and temp limits and, short of a randon failure, your system will likely be obsolete long before components fail because of overclocking.
I recommend you overclock only the CPU. How far you can go depends on a lot of things including the CPU. Small variances in the components will affect the overclock. Overclocking RAM in Intel systems generally does not help that much. The video card is already factory overclocked, so I do nopt recommend that you try to overclock it either.