Yes
Contact S&W.
It depends on how old it is. Needs to be examined by a gunsmith.
You should contact Smith and Wesson directly to get the correct answer to your question.
No
Contact S&W.
Not recommended
There is no simple answer. It will depend on the exact model and when it was made. Best to call S&W to get a correct and current answer.
Not recommended
Yes
NO
1. It can, but, it is not advised. 2. It is stated by Smith and Wesson that the model 14-3, which is the third change of the model 14 can safely shoot plus P ammunition.
Mid 80's. Call S&W and they will tell you when it left the factory. Standard Catalog of Smith and Wesson, 3rd edition.