confidential cpus are typically engineering samples, usually given to motherboard companies to work on bioses for the cpu generation and meant to be returned to the company after done. engeering sample cpus can be missing features, lower clocks and such that the retail varient may have.

as for geneeation of cpu, its easier to find out via what motherboard socket it is

on thecontext of finding second hand, i wouldnt say its common, but can happen. some chinese companies sell dirt cheap ES cpus for basic computing.

the ilm says lga 115x, so its either 1156(1st gen), 1155(2nd or 3rd gen), 1150(4th and 5th gen) or 1151(6th to 8th gen)

server markets dont shift instantly. they gradually take time to change, much more slower than consumer adoption rate even. its why the growth in the market for server matters more than the actual market share, as it shows shifts in market behavior which represent what the market wants in the future.