If you compared a "high end" thermal paste to a "low end" thermal paste, you will not see amazing temperature differences maybe a 2-3 degree difference (possibly). Any thermal paste will suffice, it more depends on the cooling solution itself such as cooling fans and the CPU cooler.
I use MX-4 as do many others and it does its job. I got it due to the fact that you get a lot in one tube.
No, but my cousin has, it does dry up after a couple of hours, but I am merely stating the basic principle that it can work for a fixed period of time of course. It was also partly a joke which you clearly did not understand, I find that perplexing.
Remember use the absolute minimum and spread it as thinly as you can - metal-on-metal is the best thermal interface and the compound is just to fill any tiny pits and dimples (which are not visible to the naked eye)...