If you haven't done this before, you really should take it to a gunsmith and have them walk you through it. Disassembly isn't so difficult, but reassembly can be, in regards to the Ruger Mk. I, II, and III pistols, and it's really not an undertaking you want if you haven't done it before.
You can request an owner's manual for free on Ruger's web site.
$100-250, depending on the condition, type barrel, etc.
Ruger has extensive sn data on their website. You will have to go there and look it up.
Value of any gun is based on make, model and condition. A Mk 1 could be worth $125-$450, depending on condition, box, papers, etc.
Ruger's web site has sn data on it.
If it's a MK II, it will be marked as such.
IIRC, 1 in 10
The value of ANY firearm is based on the exact make, model, variants such as type of barrel or sights, and condition. Without that information, we cannot offer a realistic answer. The Ruger Mk 1 may be worth for $75 to $250.
You can request a owner's manual at the Ruger website.
50-200
50-200 USD
Ruger will tell you if you phone customer service.