Have what I believe is a PST folder of downloaded email from an Optimum Online account.

  • Within Outlook how can one confirm that this is PST file/folder
  • What is the proper way to get these emails to a DVD, then check if the transferred data is correct

Simply, import it. You would wisely export your own data and clear the decks first to avoid confusion. Or, if it's not your .pst, then in a VM.
Any burner will handle the copy to dvd; decent burners allow for integrity checks on the burn (read/compare).