250 or so
Email Smith & Wesson. They keep good records and and usually responsive to questions.
Call S&W and they will tell you.
If you call S&W, they will tell you when it was shipped from the factory.
10-200 USD or so
You must provide a serial number.
100-400 or so
200-375 USD
100-435 USD
When referring to the .40 caliber cartridge, SW always stands for Smith and Wesson, regardless of the brand of the gun, because the .40 S&W cartridge was designed by Smith and Wesson. The offical name of the cartridge is .40 S&W, just like the official name of the .45 is .45 ACP (Automatic Colt Pistol). People have a habit of leaving off things they don't think are important, so the .40 S&W is commonly called just "40."
You will have to call S&W to find out.
Need a detailed description of ALL markings.