He really should have been backing up his own data anyway. And if you really have important data on your computer, why would you send it off to strangers to back up anyway? I'd format the drive and zero it out before returning it.
I do, but you still need to back up the last days or so right before replacing the drive. That is also why I didn't want to buy a HDD - I already have a back up solution.
That's not Apple's responsibility.
Try out hourly backups with Time Machine. The incremental backups are quick and comforting.