Contact S&W for the correct factory answer.
Yes
You must follow the owner's manual or call S&W to find out for sure.
No
The smith and wesson model 15,4th change (15-4) was made by smith and wesson in 1977.
With the serial number that you have supplied,your Smith and Wesson model 15 was made in the year 1950.
15 yra
The user.
I can say that your smith and Wesson model 15-2 .357 magnum was made between the years 1961-1966.
If you have enough money, time and a really good gunsmith, anything is possible.
1977-81
50-275
50-500 usd