I use a back tension release for all of my target shooting. I would suggest that you find someone who is very proficient or go to a shooting school to learn back tension if you are interested. I went to the shooting school and it helped me out tremendously. My scores went way up to 300's and above with the right technique and practice.

To help with part of your other questions. Back tension is just that, you use the muscles in your back to execute your shoot. Using back tension the right way allows you to just concentrate on aimimg while you subconciously execute your shoot ultimately creating a "surprise" shot. Accuracy in turn increases because of your dedication to the aiming and not the control of the release aid. Many people have trouble with back tension because they want to punch or force the release to go off which causes a level of inaccuracy.

I hope that helps you some as many others may be able to give you a more detailed account. Good luck.