Will drive flush cache on cable disconnect?

Sorry I am slightly OT

If I disconnect the SATA / SAS cable, or I suddenly power off the computer with the controller (this can be done if the drive is on a JBOD chassis with separate power) will the HDD/SSD go ahead flushing all write-cache content to the platters / flash media? (and so I would get a consistent filesystem/database on power on)

Or will it get mad when it returns completion for each write command and nobody is listening on the other end of the cable? (cable disconnected or controller powered off)

Now another question:
When the drive is doing cached writes (cache on), without NCQ (queue_depth at 1), is the "completion" returned immediately upon receiving the write command, or is it returned later when the data goes to the platters? If it's the latter, what is the difference with NCQ (queue_depth > 1) then?

Thank you