1966 Rolex Tiffany & Co. Questions

[goodmake]

New to Rolex Forums. Just a couple of questions regarding the attached. Who's the authority on Tiffany & Co. branded Rolex models? This one was received by my father-in-law when his brother died. It was given to the brother as a retirement gift in 1966. I thought all Rolex models had the serial number and model engraved at the 6 and 12 mark but this one doesn't. However this one apparently came with a leather band. Does Rolex still include the serial number in those locations when a leather band is used? Also the apparent gold is tarnished. Does that mean it's gold filled? There does not appear to be any gold hallmark on the case. No papers.

Thank you very much for any info. I do appreciate it!