If it's an older gun it's likely 1:14 twist. Most of them were.
50-550 usd
ABOUT $700
I know smith and Wesson sells them and maybe ruger. not so sure on ruger
It will be marked on the barrel. You can also call or visit ruger's website.
It is a revolver. Value about $250, depending on exact model and condition.
$500-$700, depending on exact model and condition.
I do not believe the RG 14 is a Ruger. These were inexpensive German made handguns (Rheinmetal Gemeinschaft) that sell for $25-$50. IF your firearm is marked RUGER on the barrel or frame, I could be wrong. If it is marked RG, not a Ruger.
$250-$500, depending on the EXACT model and condition.
Around $600, depending on model and condition.
You can measure the barrel yourself if you have it, using a steel tape measure. You can also contact Ruger Customer Service through the Ruger website. There is no published data that gives the barrel length of each firearm made by a given company, only the standard configuration for a given model- and THAT varies.
100-500 USD or so
100-1000 SUD depending on EXACT model variation.