[eleusive]

(Disclaimer, I'm not an expert, but I can squat well over 1.5x my weight for several reps)

For squats, you should make sure to go parallel and "sit back" at the bottom of the movement, while pushing your knees out to the sides as you go down. This takes the stress of the weight off of your knees and onto your posterior chain. Otherwise you'll get hurt knees just as you described.

Not sure what could cause that deadlift problem, other than maybe trying to lift with your back before the bar clears your knees (which until that point your legs should be doing most of the lifting).

FWIW, it took me a long time to really get comfortable with my technique in the heavy compound exercises, but I've seen remarkable gains from them once I learned proper technique.

If you're really serious about doing the core exercises with proper technique, I strongly recommend picking up a copy of Mark Rippetoe's "Starting Strength" book. It goes into great detail the correct technique and mechanics behind the exercises.