These ones from Carolyne:
"I'm not clear on whether I'd even be able to teach at a Uni in Korea with my qualifications."
Carolyne has a Master's Degree and is a USA certified teacher. She is more than qualified to work at a Korean uni. Most hiring committees love "real" teachers and she'd probably get hired in no time.
"I've also heard that Korean culture can be very ageist, so I might not be considered for hire at the 'advanced' age of 46."
Many unis actually prefer older teachers, as opposed to the hagwons who look for the youngest and most fabulously handsome they can find. Many of my co-workers are older than you.
"I would like to hear a little bit more about your take on the public school situation vs. Uni, which is where I'm most interested in looking."
In almost all respects, unis are better than public schools in Korea. The starting salary is usually higher, and you'll have more overtime opportunities. You'll also work fewer hours and have more vacation at a uni.
The thing I like best being at a uni is that I'm totally responsible for my own classes. I have no co-teacher, which from what I've heard is a major source of frustration for public school teachers. And I have complete control over grades, which gives me a large degree of power. In public schools, your classes often have no impact on student's final grades, so it's hard to really have any respect in their eyes. It's like your classes don't really matter at all.