Start at your local library.
Well, that's one place to go - check a copy of the "Blue Book of Gun Values" by Steve Fjestad - look under the Harrington & Richardson Inc. identification section. You'll need to determine model. With that "S" prefix it could be a pre 1940 Hinged frame, 9 shot Single Action Sportsman, or it could be any of as many as a dozen other models made in 1956. Big difference there.
More information needed to determine model of firearm.
Consult with a good gunsmith.
25-150 USD or so
$100, more or less
$50-100, depending on condition.
No way to tell.
"BB" prefix indicates 1985
Not enough information provided for clear answer. Description of type of "pistol" - semi-auto or revolver, markings on firearm, type of action, etc. needed.
@ turn of the century; less than 100 USD
H&R made utility firearms from 1874-1986. 50-100 USD
Have you tried a web search? Local Library? Do a web search on Harrington and Richardson Books and you will find some sources.
1971