Oh man… when it comes to thermal paste you need to use enough to cover the chip completely. If a little oozes out it is okay AS LONG AS IT IS NOT A CONDUCTIVE THERMAL PASTE! Ones like Arctic ceramique are fine to squeeze out since they do not conduct electricity. If you are going to use something like Arctic Silver then I would be especially careful since that one IS conductive.
Be sure to use really good quality thermal pads since they can move the heat away from the chips more efficiently which will make it last longer.