Unless the hdd is stored in a high moisture environment, your data should be safe enough. Worst case, the spindle of the motor gets stuck but even there are ways to get the data pulled

Depends on the planned use and the ones doing the refurb.

Generally, used hdd for cold storage is fine but constant running might not ge advisable

It’s probably because of a physical limitation, kinda like what happened to magnetic tape back in the day. Give it a couple decades, the same thing would probably happen to ssds

It’s probably because of a physical limitation, kinda like what happened to magnetic tape back in the day. Give it a couple decades, the same thing would probably happen to ssds

Yes

Yes