I don't want to sound presumptuous but do you have a 120hz monitor?
u dont need 120hz to see the difference between 60 fps and 120fps, for the same reason u see the difference between Vsync on or not.
So, as far as I know from my limited tech knowledge I don't think the monitor actually makes any use out of frames higher then 60. The 60hz refers to the amount of times the screen refreshes an image per second
Yes, thats correct. 60Hz is the image refresh rate, so the unit of frequency and defines number of cycles (frames) per second.
so unless you had a 120hz monitor then I don't think the extra frames really do anything aside from tax your system more for no added benefit.
No, because the graphic card doesnt work synchronous to the monitor. You see the difference really good. I cant play CS:S with less than 90 fps, i need steadily 100 fps. But one way or another, for sure the image get better (Smoother/Faster) if u have a 120hz monitor instead of 60Hz.