Can only answer to your first question. I've found the recoil on my P99 QA to be managable once you get used to the gun, which I am still in the process of. What I've found is it's difficult to adjust the sights on the gun to aim where you want. This is probably due to my inexperience more than anything else, but I had them dead on one day at the range and decided to play with them more to see if I could get them right again, and it's never shot as accurate since and I try and find that sweet spot every time I go to the range.

Over the P99's a fantastic gun. BTW, in regards to your arthritis, you can adjust the grips so maybe to lessen the pressure of the recoil on a particular part of your hand. Just a thought.

the trigger weight on the AS is 11lbs first and ~5lbs there-after while the QA model is ~8lbs. most people will tell u they prefer the smooth AS version.

i have only shot the QA so i cant comment if the recoil is felt differently or not.

Answers:

1)a. Recoil is similar to all other quality polymer 9's.
1)b. Recoil is constant. It does not change with the number of rounds fired.

2). No difference in recoil. The trigger type of a gun has zero impact on recoil.

3). Any company that does aftermarket refinishing can refinish the slide of a P99 - or the slide of any quality handgun for that matter.

Suggestion:

If arthritis makes you over sensitive to recoil, don't but a polymer gun. Buy a big, heavy, all steel gun. The extra size and weight will do wonders lessening felt recoil.