3 Answers

No. Coffee sets are silverplated and the "800" is the pattern number. That mark was used on holloware between 1938 and 1976 and was part of the International Silver Co. at the time. 

James Stacey more or less wrote the book on link the highly collectible world of early Audemars Piguet Royal Oak Perpetual Calendars and Pharrell owns link a pair link of superb examples. The two watches up for grabs are different examples of the skeletonized ref. 25636 one is cased in platinum and features a Mark 2 dial and another is cased in yellow gold with a Mark 1 dial.

Speaking from the perspective of this vacation-class diver you could definitely still use this bezel for a dive especially if the plan was to use it as a backup for a dive computer. So link yes as a Pelagos nerd I always find it unnerving to see a new model that isn't primarily designed to link be a dive watch but as Tudor expands the link Pelagos to become a sort of catch-all for its modern sport watch designs a GMT isn't all that shocking especially compared to the cycling FXD linked above.