I didn't pay enough attention to the opening comment in your message; didn't realize you had posted some of same information about 6 weeks ago.
Staph aureus also can be a contaminant, i.e. picked up in a culture just because it was on your skin - in which case it doesn't matter. Before you go off to an ID specialist, discuss the results and what they mean with the doctor who did the culture test.
HHH, MD
Staph aureus is a very unusual organism to cause urethritis. But if you're having purulent (i.e., yellowish, creamy) discharge and the culture was positive, it seems a good bet. However, the symptoms and the nature of the discharge are identical for gonorrhea and sometimes for chlamydia, so make sure your doctor tested for them. Those of course are STDs, but staph is not. And you might have more than one infection; gonorrhea, chlamydia, or nonchlamydial NGU (nongonococcal urethritis) could set the stage for a secondary staph infection. Staph, but usually not gonorrhea (and never chlamydia), could also cause infection higher up in the prostate or seminal vesicles, turning your semen yellow.
Presumably you were examined right after your discharge started, yes? What treatment was given?
My advice is to see an infectious diseases specialist ASAP. If you really have a Staph aureus infection, it could be quite serious. Most medium to larger towns have ID specialists; if there is a major medical center, for sure there will be an ID doc. You could phone your local medical society for a recommendation.
As to your specific questions:
1 and 2) Staph bacteria are on our skin and all around the environment. It is difficult these days to predict the best antibiotic; a test has to be done on the staph itself to see what antibiotics it will respond to.
3) See above about yellowish semen.
4 and 5) Wrinkled skin and you testicular discomfort don't sound like anything serious, certainly not as important as your urethritis. You may be noticinng minor symptoms more than otherwise because you are anxious.
6) None of these problems, or anything else, would make an HIV test inaccurate. Nothing you describe sounds at all like HIV; you can rest easy about that part.
My professional advice is above: See an infectious diseases specialist soon.
Good luck-- HHH, MD