why I can only see the keywords down to the letter R, and not all of them, at that?
Most likely because you're on Windows, you have more than about 1500 top-level keywords, and you're running into a long-standing limitation of LR on Windows. See this help article for a workaround: Keywords missing. It's been an outstanding bug for many years.
why despite confirming the case of the first letter of a Keyword ie. a person's name, as being upper case, in the Keyword List, does it continuously appear as a lower case letter when I enter the name in Keywording?
When you enter a keyword in the Keywording panel, and that keyword already exists in the Keyword List, LR will always use the case as it appears in the Keyword List. So, for example, if you have a keyword "Evyn" in the Keyword List, and you enter "eVyN" in the Keywording panel, the photo still ends up with the keyword "Evyn" assigned to it. You can change the case of the keyword by right-clicking it in the Keyword List and selected Edit Keyword.
I don't know why the case appears differently in the auto-completion in the Keywording panel. But that doesn't really matter, since LR will use the case as it appears in the Keyword List regardless.
other misspellings of the name pop up as suggested keywords
If misspellings (as opposed to just different case) are showing up as suggested keywords, you might check the Keyword List to see if those misspellings have made it into your list and possibly assigned to photos.
Thanks for your reply. I'll try to group words to reduce the length of the Keyword List. Always leaves one incredulous, when a known problem isn't addressed in a permanent way. As for the misspellings, and cases, I'll need to keep a closer eye on those variations.
Again thanks for your time.