Guys, this may sound like an idiotic question, but I was wondering if any one of you have tried to burn an iDVD img file to an external DVD recorder (NOT A BURNER) by using either Toast or Disk Utility.

Remove the DVD Burner from the recorder. If it's one of the ones supported by the MacOS, and it has an interfacce that maatches your computer, then put it in your computer.