NTBackup is native to windows and fully supports backing up exchange in an active state. So you do not need to shut down any part of exchange if that is what youre asking. It shouldnt cause corruption just because exchange is running at the time of backup.

NTbackup does not support mailbox level backup so far as I know so it would be a disaster recovery backup situation, not an archive situation. You would have to dump out and restore the entire mail datastore at a time. 

you can start ntbackup i think by just typing ntbackup into a run dialog or cmd prompt on windows, its fairly automated and beyond the scope of this mailing list to detail how exactly ntbackup works. Basically run ntbackup and create a nightly job that dumps out the exchange data store before the backuppc process happens. I have two jobs, one for even days and one for odd days, they run every other day respectively and overwrite their respective file each day so I dont have backup file buildup on the system. 

As far as vss snapshots, that is fine for flat files but my understanding is that is a lot like trying to backup a sql database file, you are backuping up an active database file and who knows what state the file is in. You really should be doing a dump of the database and backing up the dumped file, be that exchange or sql or anything else. I'm not entirely sure how exchange would feel about you trying to restore a flat file of its database either. You could end up with exchange rejecting the restored file. I dont entirely know on that last bit to be honest though.