The factory cuts are the easiest to duplicate because the angle is already known. You simply transfer the angle from the end of the rail where the facing attaches to the cushion,one thing to remember is its not a straight cut ,it angles down slighty, this takes practice and you can practice by removing the original cushions and sliding them down the rail and cut them a few times .
Alot of people have posted pics of thier pockets after the cushion angle has been changed, to do this you need to add whatever size wooden shim you need to make the desired pocket size and then cut them back towards the end of the rail at a 45* angle, not the easiest thing to do for a beginner but maybe someone else can explain that more clearly.
The size of the pocket is determined by the cut of the cushions, not the profile so you can make any size pocket with either cushion.
No. 6 pockets bolt to the rail thru a bore in the end of the rail, no.3 pockets bolt down thru the top of the rails.
Most facings are leather but some are impregnated with a harder compound of some type to reduce ball bobble in the shelf area.
Alot of the older tables are chewed up along the bottom where the staples go making them tuff to work with, clean them up as best as you can and use a longer staple like a 3/8 in so they sink into the rail beyond the ruff surface.You could repair the surface like you say but you may get some cracking or chipping when you restaple.
There is no way to extend the shelf further towards the back of the pocket.
If you can improve on the original ball box by all means go ahead and just give it to the buyer if you sell.
