You can restore just a file - you have to tell it where - ex:

First you have to tell it the drive the tape is located in - ex - our drive
1 in one of our ATL robots is dev/rmt/0mt - 

Then the location of the file <filespacename>:\winnt\system32\odbc.ini

Best thing to do is to look at the Admin book of the platform of the client
I think each platform has a different syntax.

Yes, backupset is the same name as instant archive. Personally, this
functionality needs enhancements and many of them - such as automation, a
faster way to retrieve the files, etc.