You probably have a Mk. I pistol, manufactured circa 1958. If this is the case, it would be a semi-auto pistol, chambered in .22 Long Rifle.
50-300 depending on specifics
Unaware of any maker by the name of Rugar. Ruger, however, does make a Mark II. Value range 100-200 USD
It doesn't exist. Now a RUGER, Mark 1 you can get a manual for from the company website.
If the new Ruger web site is working, it has extensive sn data.
about $230
@ 4kilos
50-500 usd
Neither, it is a Walther.
No such maker known.
Yes, but, not recommended
up
Winchester 44 Magnum.