I think you're getting thrown off track because you're looking at the case and not the drive. These kinds of external CD drives are nothing more than a standard, off the shelf SCSI CD burner inside an external case. The case provides a power supply for the drive and a connector adapter to allow the external SCSI cable to plug in - and nothing more. If you want to find out what drive is in there, take the cover off and look at the drive.
But, it doesn't even matter what drive it is - it's a SCSI CD burner, they all work the same. Plug it into the Mac and use it as a CD reader - if you want to record, you'll need burning software (and the Mac needs to be fast enough). Toast is the most common Mac CD burning software.
The Quadra 800 is only a 33mhz '040, IIRC - you might be able to burn from it, but I'd keep it to 1x speed.
Don't forget to use a SCSI terminator...
-Ian