vectorinvestor - its tough to say without seeing your swing but from your description you are probably too upright at the top of your swing - possibly because you are lifting your arms and not turning your shoulders. I would go and see a pro and see what he says but from your description i would be thinking along the lines of flattening your swing at the top. From here you should be able to drop easier onto the correct plane. As tomallinder said, its not an easy one to fix. If you cant get to see a pro then go buy one of my favourite golf books - nick faldo's swing for life. He flattened his swing and calmed his leg action down and this book would really help you (or anyone).

By the way your heel coming up early in down swing is a result of your lifting/upright plane and not a THE cause of downswing problems. Fix the backswing and the heel will get fixed naturally.

these are only my opinions and a pro who can see your swing should be able to help.

hope this helps

nick