1. Weightlifting shoes help with most things in weightlifting. Do-wins definately help the most.
2. Form breakdown is not uncommon in 100% lifts.
3. Drifting forward is usually caused by one of two things. One is raising your hips too fast, faster than your chest, which causes you to lean over. This is usually because you have weak quads. The other is the upper or middle back collapsing upon catching the bar or while you are standing up. I suppose this could be from a weak back, but more likely it is either because you have caught the bar in too much of a leaned over position, or because you simply arent adequately controlling your musculature, you just arent holding the back tight. Me seeing very strong guys, with very impressive back musculature, have more problems than anyone with the back collapsing when catching the bar or rising with the bar has convinced me that it is rarely a lack of muscle or actual strength that causes the back to collapse.