Sometimes I get holes in the drywall mud after it dries... what causes this. You can almost tell when it will happen because when you are putting the mud on the wall it kind of bubbles. I like to mix the mud because it seems easier to work with... mixing it wouldn't cause this would it? Also would like some tips on things to use for doing fancy ceilings. I use what looks like a 6" round broom and I kind of punch it on... but I am looking for more of a circle type of pattern.

You are holding the drywall knife to flat. Think of it not as smoothing the mud down by pressing on it, think of it as cutting the top of the mud off smooth. Just get a little more angle on your knife