You should call S&W to get the correct answer from them.
You must call S&W for a correct answer.
The markings.
500$
yes
Best left to a trained gunsmith
50- 325 USD or so
100-300 usd
I would start my search at Smith and Wesson first.
Pure energy (PE) manufacture steel tanks that have a PSI rating of 3000. and also make aluminum-carbon fiber wrapped tanks that have PSI ratings at 3000 and 4500P
100-3000 depending on specifics
You will have to find someone who specializes in air gun repair.