The squat can be one of the most technical lifts when you really get down to it. That is one of the reasons that I usually just do front squats. Regular squats have always been weird for me, and are really hard to get right. Front squats are very natural for me, and I just prefer the feel of them a lot more. I do them with a cross grip, and never have trouble holding the bar. This seems to be a problem for a lot of people, but it has never bothered me. Just keep your elbows high, and have the bar tucked between your delts and clavicle. It's important to try and have your torso as vertical as possible for the whole lift. Tight abs and sitting back works for that.
Hopefully Pudge comes in with some advice on the overheads.