Yes you can resore individual items from the Exchange store. Not just email messages, you can restore calendar, tasks, etc..
It is really quite simple to do. I have found that according to the users guide, the Information Store will need to be dismounted and then remounted after the excerise. I have always selected "mount after restore", but to be honest, I don't think it does dismount the store. Generally speaking, it takes a minute or two to dismount the store and then remount it - I have never noticed the store to go "offline" while doing a restore to exchange of an individaul item or even someone's inbox.
When the restore completes, the items that were restored are back in the users mailbox. Backup Exec sends that user an email explaining that some items have been restored.
When I restore individual mailbox items, I select the following:
Restore all transaction logs, do not delete existing transaction logs (no loss restore)
Commit after restore completes
Mount Database after restore
I DO NOT select "Dismount before restore".
If you are concerned about what to select - use the "Guide me" solution.