Definitely yes on keeping those heels down!:) Think of your position as dropping your weight down a straight line, from your ears to your shoulders, to hips, to heels. Also don't rotate your pelvis too far forward to the point where you have an arch in your lower back (first picture in the diagram). Look up, shoulders back, chest out. Keep your abs tight, like you were being punched in the stomach (haha). That will help you have a nice straight back, like in the second picture pelvic.jpg
Overall looks awesome! Pretty horse!
"You are a great champion. When you ran, the ground shook, the sky opened and mere mortals parted. Parted the way to victory, where you'll meet me in the winner's circle, where I'll put a blanket of flowers on your back"