Some NAS drives will support Time Machine backups and some will not, so you would need to check with the drive manufacturer in advance to make sure that the drive you were interested in will work correctly.
Time Machine on one given Mac can only backup to one destination drive at a time.
You can change the destination drive(s), but you would have to do this manually in Time Machine Preferences.
Kind of clunky, but it would work if you remember to switch drives each day or week, etc.
You'd probably be better off to let Time Machine back to your TC, and use a different app to back up to your NAS. CarbonCopyCloner can do that. I don't use SuperDuper, but it might be able to.