This is really a lot of worry for nothing.
1) Is it true Cunnilingus is extremely rare for a man to contract throat Gonorrhea?
Yes.
2) Is is true that Cunnilingus is even rarer to spread Oral Chlamydia?
Yes.
3) is it possible that a oral gonorrhea could move from my throat to my prostate?
Absolutely not. There is no pathway from the throat to the prostate.
4) I've read that it's believed nearly all Pharyngeal Gonorrhea cases will clear untreated without any issues given time - true?
Yes, this is true. We would never advise someone who thinks they have an oral STD to just wait for it to clear, but yes, this is true.
5) How obvious are DGI symptoms - I'm scared an infection might have spread silently.
It is obvious. This happens when the gonorrhea bacteria enters the bloodstream. You'd likely have arthritis-like pain, sores on your body, stiffness in your joints, a rash, or a combo of those symptoms.
6) If DGI was untreated would it continue to get worse? Like would I be really ill?
Yes. You would have sought treatment by now.
According to the CDC, DGI is uncommon and thought to occur in 0.5-3% of untreated gonorrhea cases.
If you are so concerned, get tested. Ask your doctor for throat swabs. Then let it go. You will be negative, I'm sure.
Also, maybe talk to your doctor about your anxiety. Your reaction to this is out of proportion to the risk level, by far.