At various times barrels of that length have been made.
No, no, no. Do not attempt to do this.
If you go to You-Tube and type in disassemble of Smith and Wesson model 915;there should be a video of the steps needed to take down your smith and Wesson semi-auto 9mm.
You can request a owner's manual for free at the SMITH AND WESSON web site.
Can't be answered without knowing what model.
100-400 USD
100-1000 usd
100-400 USD
value depends on overall condition
100-600 usd
100-500 usd
50- 650 usd
50-400 usd