The Ruger SR9 uses a proprietary magazine.
No, they do not use the same magazines.
It doesn't.
Try e-gunparts.com or Mec Gar
I paid $439 for mine at Outdoor World. MSRP is 525
No
No, the magazines are not compatible.
Can't be answered without a DETAILED description of ALL markings, to include label on box.
I have seen very few used SR9 Rugers at my local gun shops. However you can buy a brand new one for around $360.00. That is a pretty good deal if they get some of the bugs worked out.
No.
Best left to a gunsmith.
From the Ruger website: What type of ammunition should I use in my Ruger 9mm pistol? The Ruger 9mm pistols are chambered for the 9x19mm NATO Parabellum (9mm Luger) cartridge, compatible with the U.S. and foreign military or commercial 9x19mm loads manufactured in accordance with NATO, U.S., SAAMI, or CIP standards, including high-velocity, subsonic, tracer, hollow point, ammunition loaded in aluminum, steel, or brass cartridge cases, +P and +P+ ammunition.
Primarily in the magazines; Mark II has a bolt hol open also