You need to rotate your hand out until your knuckles are at a 45-degree angle; it looks like you're holding a hammer now straight up and down. Let your fingers go completely limp; some people refer to it as "dead spider legs" -- you'll see people stick their fingers straight out in an effort not to hold on to the bow, but that's just as wrong. The idea is to get the tension out of your hand, and more specifically your forearm.

After you rotate your knuckles so that they're positioned at a 45-degree angle, the throat of the grip should rest lightly against your thumb pad -- just to the left of your lifeline. There shouldn't be but about an inch of the grip actually making contact with your thumb pad, and keep the heel of your hand off the grip as well.

Some people LIGHTLY rest their first finger or possibly two on the front of the grip as well.

Start there, and then work on standing up straight. I think it's impossible to tell anything about draw length until you place your weight evenly on both feet and stand upright to start with. Work on making that perfect "T" first.