Types and reason to use of not

@gregchick0

are optical outputs of my 6006 CD player better to use to my preamp than the RCA, or are the Coaxial ports better to send to the preamp?

Not meaning to be rude, but why not join the club, and try each, and let your ears determine which sounds best to you. That’s pretty much what all of us here do. What sounds best in your application could depend entirely on your components.

The AES/EBU port on back looks like an XLR, but is a single port, not L & R.

If you're going to use the AES/EBU XLR connection, make sure the cable is rated for AES/EBU service, and is a 110 ohm cable.   

I know nothing about Lear Jets

You mentioned 8-tracks, and I believe William Lear and Learjet Corp. designed the 8-track tape. 

 I was wanting to avoid spending money on a cable that was not needed. 

In this hobby, we audio-enthusiasts try different combinations of cables and equipment. We're constantly in search of the best audio reproduction we can achieve with our gear. Many of us simply use our ears to determine what sounds best to us in our environment. It's all very much a learning experience.  

@gregchick0

The AES/EBU port on back looks like an XLR, but is a single port, not L & R.

That single AES/EBU digital XLR actually contains L&R stereo audio.