Overclocking will only significantly impact on lifespan if your cranking voltages or running at high temperatures, and if their doing it proper then both will stay reasonable.
"Superclocked" is just EVGA's marketing department talking, all it means is that it comes clocked higher from the factory than Nvidia reference specs says that card should. No reason (other than voltage, temperature and acoustic limits) it cant go higher.
Often factory overclocks are pretty conservative, I bought a reference clocked Sapphire 7870 around launch, clocked it a good 150Mhz or so higher than the overclocked version they released.
so. Do you think I should overclock my GPU? I kinda want my GPU to last long, since it's GTX970 (I don't think I'm going to upgrade my GPU for a while)
Also, is overclocking CPU
worth it? On this page it says it can overclock to 4.0 -> 4.4 GHz
I'm too scared to overclock anything from the fear of that it will shorten the life span