Yes. And btw that is what naturally happens after about age 40, together with presbyopia. So real absolute pitch people stop enjoying listening to music at some point... it is a curse, not a gift!
More difficult. Also little people affected, so not much research going there, and most important, is just a nuisance, not a problem like not being able to see.
No. I think a lot of people would notice. Especially string players.
A lot of orchestra musicians don't like listening to recordings that deviate too much from their preferred concert pitch. I don't like listening to British or American recording where a equals 440 or some old German ones at 445-446. That is less than 20 cents.
This same prank would have no impact on someone who memorized approximately where A440 is by listening to a tuning fork every day for 10 minutes.
Absolute pitch and tonal memory are different physical phenomena.