RE: back tension
Back tension is the most accurate method for shooting a release. BT can be used with caliper, thumb trigger and obviously, pure BT releases. I hunt with a Winn Freeflight release and you cannot shoot that style of release with BT. This is because the wrist strap encompasses the whole release hand.
The act of back tension is done by creating a push/pull tension with the bow arm and the release arm,by usingthe back muscles. When at full draw and anchored, stabilize your body with your back muscles. This should allow you to have a completely relaxed bow hand and release hand.
The next step is to set your trigger finger/thumb. For a thumb release, you curl your thumb up and lightly rest it on the trigger. Careful, Carters can have an extremely sensitive trigger. It's something you'll have to play with. It is best to stand up close to a blank bale and try this until you're comfortable with it. Once the thumb is set, start the push/pull with your back muscles. Keep both tensions (push and pull), in the same plane. As the release arm moves backwards (it is barely perceptable) the little and ring fingers will want to naturally move farther than the other fingers and will rock the trigger into your thumb, thus setting off the release. It WILL be a complete surprise to you! Sometimes it is good to practice with your eyes closed in order to get a feel for this type of shooting. When trying to aim and hit a target, all you should be doing is aiming, aiming, aiming.... until the release goes off. This is what makes BT so accurate. Your only job is to aim, the release becomes automatic. It stops you from punching the trigger.
Caliper releases can aslo be shot with BT. I call it the hook and pull method. When you draw your bow and anchor, hook your index (trigger) finger over the calipers trigger. Hook it deep, at least to the first knuckle if not half way to the second knuckle. Then start your tension and finish the shot as mentioned above.
Pure BT releases. These have no visable trigger. I like the Stanislawski models. For indoor, I prefer the two-finger stan. You draw the bow with one finger then after getting anchored you carefully hook the second finger, then start your pull.
Perfecting your shooting form by shooting back tension will really improve your accuracy and consistancy. But remember, at times, hunting situations differ from target situations and you may have to force the shot or trigger the release when the mind shouts "NOW!". Not the best situation but sometimes happens.
As I mentioned earlier, I hunt with a Winns release. I will be switching this year to a Tru-ball Tornado, caliper so I can use BT. I believe it is the best way to go. Although for target archery I shoot Stans or Carters, I prefer a wrist strap caliper for hunting.