If you go to Ruger's website you can download the manual for your mini 14 for free. It tells how to disassemble your gun in the manual.
100-460 or so
500 US Dollars
The original, factory Ruger Mini 14 folding stock used wood. The folder itself was steel, and was an 'underfolder' design, similar to the type used by the AKS-47, AKMS, etc.
500 US Dollars
100-500 or so
The Ruger website, under Customer Service, has a downloadable owners manual for your Mini 14.
580 is the newer version of the Mini 14 Ranch, minor engineering changes, improved accuracy, etc.
$350 to $800, depending on WHICH Mini-14, and condition.
You can contact Ruger's customer service to find out.
It says it can on Ruger's website.
Ruger has sn data on its website.
You will have to call Ruger.