You've got a 73" reach. My wingspan is 83". That's why I have to take steps to shorten my draw length.
No. Closed stance shortens your draw length. Open stance lengthens it. Maybe you've confused the terms. I had a heckuva time with it when I started learning karate and this is how the master explained it to me, and got me straightened out.
Imagine your body is a door and your front foot is the door hinge. Pivot on your foot so that you are facing straight at your opponent (in our situation, the target). You've CLOSED the door, or closed your stance. Pivot so that you are facing 90 degrees away from your opponent (the target) and you've OPENED the door, or opened your stance.
I used to stand facing a full 90 degrees away from the target. Now my stance is about60 degrees. If I close it up any further, it hurts my shoulders, puts my shoulders way out of alignment. But that's how closing the stance shortens the draw length.
Keeping your head straight IS important for consistency. If you lose your composure, you'll never hit nuthin! Ohhh.... You mean head POSITION.

[8D]Yep. Keep the head upright. That's good ol' target form and what you have to do to keep the coach happy. On the other hand, if you lean your head exactly the same each time, consistency doesn't suffer.
Anchoring on a tooth is a good idea and is taught by some of the top shooters, but it's not really common. Most folks just pull to the corner of the mouth and let fly.
But yeah, I do believe you're in danger of over-thinking the draw length thing. First, make sure your form is good and then, whatever you draw with the recurve is what you draw. How it compares to your draw length with the compound is absolutely a moot issue.