The serial number. Ruger's webiste has extensive serial number data you can pull up. Go to the product history link on that page under customer service tab.
100-350 or so
A call to Ruger will get you the answer.
Request a manual from Ruger on their web site.
$100-$430 or so, depending on condition. USD - United States Dollars
100-400 USD
$100-$250, dpending on condition.
No such model. There was a SP101; 100-300
100-400 USD depending on specifics
15 or 25 yards
125 or so
100-400 or so
You can request an owner's manual for free on Ruger's web site.