eBay has reproduction manuals on occasion. Keyword Remington Model 12 and it should take you where you need to look.
1911
1914
Depends on condition, condition, and condition. Anywhere from $200 for working beater to $1,000 new in the box w/ all paperwork. In the very good condition $500-600 that's lots of blue and good wood with nothing more then general handling marks.
Early 1920.
The Remington model 12C slide action 22cal. was produced from 1909-1936.
Bottom of receiver in front of trigger
Manufactured 1914
1919
1920
Late 1911
No way to answer without the serial number.
The 2012 McLaren MP4-12C has a 7-speed automated manual.