Nope you dont have to touch anything, Haswell refresh chips like the i5 4960K are fine on the Z79 platform, its just the Z87 platform wont work straight out of the box with haswell refresh
That would be ample cooling, I forgot about that one Im actually buying it for my i5 4960K rig aswell that Im building currently - not sure how I forgot xD
About the motherboard, Do you have any experience about that one? was reading that you needed to reboot the computer if u overclock the CPU or GPU, cant remember if its just one of them or if you OC both.
Nope you dont have to touch anything, Haswell refresh chips like the i5 4960K are fine on the Z79 platform, its just the Z87 platform wont work straight out of the box with haswell refresh