Ok, here is my response to some of your questions:

1. Fatigue (lethargy) still exists, how to reduce/eliminate?
It can take a few weeks or months for your adrenal glands to recover from prednisone. I'm not sure there is anything you can do to hurry that along.

2. Muscle loss -resume regular routines?
I would suggest you start at a lower level than before you got sick, and then see how you handle that. If it doesn't wipe you out, you can build up from there.

3. Shoulder pain - exercise routine helping or hurting and ongoing or aggravating pain?
You can try to treat it yourself with exercise and OTC medications like ibuprofen, Tylenol, etc, but you might need a doctor's advice and maybe physical therapy for that. Stopping prednisone allows the normal aches and pains of aging to come back. Whenever I have a problem I can usually find good advice in YouTube videos about how to take care of the problem.

4. Sleep - 1.5 to 2 hrs max sleep period all night, wake up, pee back to sleep. Tried, not drinking liquids, drinking liquids, reducing liquids, nothing seems to work?
I peed a lot of night when I was on high doses of prednisone, but since you're off of that, it's probably a prostate issue. That's something else you might want to check with a doctor. Have you had your blood sugar checked? That can also cause problems.

12. Research supplements and foods ...
For strengthening bones, besides vitamin D and calcium, you should also take vitamin K2. I take a single pill that has all 3.

14. Vaccines – when to take flu, Covid, RSV after Predisone withdrawal?
I'm not sure if the fall vaccines are even out yet in the US. I'm planning on at least getting the Covid and flu shots around the first of October, even though I take Actemra. I plan on getting them at least 2 weeks apart so as to not hit my immune system with too much at once.

15. No mental degradation, no headaches, no memory issues other than dizziness, but still comes and goes, especially when focusing on short putts? How or when does this disappear?
The dizziness could be another sign of adrenal insufficiency, like in your item number 1, fatigue. Hopefully it will go away in a few weeks or months.

You were lucky to only have been on prednisone for 5 months. I hope your PMR stays inactive.