A bow stacking simply means the bow draws an even weight for so many inches then all the sudden increases in draw weight per inch. For example,
If you are drawing a bow and it draws 2 lbs per inch but when you get to 20 inches it jumps to 5 lbs per inch.
A good 20 yard group is achieved by working on proper form and perfecting it. A 3 arrow group within a 4 inch circle is pretty darn good, IMO.
But, in hunting, it is the 1st arrow that counts. If you wish to be a good shot while hunting, then work on your form at 5 yards. Work on instinctive shooting at different unkown yardages. One arrow, one shot. Move to the next shot. That's why I feel stumping is a great way to learn and become a proficient traditional shooter.
A 20 yard shot, easily achieved if YOU have the skill and ability to make it. Just takes practice and good hunting ethics. If the shot doesn't feel good, no matter what the distance, then don't take it. Simple as that.
That's a great bow to learn on. Not worth much.
A glove or tab is used to protect your fingers from the string. Some tabs are made to allow a cleaner release but, still protect your fingers.
A 45# bow will effectively harvest a deer. Use a 450 to 500 grain arrow with a razor sharp broadhead and put the arrow in the vitals.
Best of luck to you.