There are some pastes that are better performing than others. Plenty of testing done on the subject which is easily found on YT and think even TH has an article about it.
In my own opinion, unless you just want to order more, use what you have.
Typical amount has been related as a "pea sized" amount. I have seen some reviewers/builders doing an "X" on these larger heat spreaders. So long as what you are using is non conductive (which most heat pastes are) then the only thing putting too much will do is make a bit of a mess around the socket that won't be seen until you take the CPU cooler off. Be careful not to get it down IN the socket.