Lots of information to absorb, Wylie, hope your head is spinning less
DE filtration is a good decision, filters the finest of particles, and will work very well for you if you choose to use Trouble Free Pool Care (TFPC) and avoid ever letting your pool become a swamp. Even if you do, it's just slightly more effort to clean the filter. If you get a lot of dirt in the pool for some reason, such as being next to a big source of dust, people also have good success with other filter types.
One of the great things about this forum is that there's experts here who will correct advice if it's incorrect or misleading. TFPC is based on decades of real pool experience across 1,000s of pools. The history behind TFPC is a great story, and the passion of the people supporting TFPC revolves around keeping people safe, having beautiful pools, and never having their pool turn unexpectedly cloudy or green the day before a party!
In addition, the reasons why TFPC works reliably has been backed up with thorough explanations of the CYA/FC relationship and other water chemistry. The vast majority of the information is backed up by peer-reviewed sources. The "deep end" explanations usually highlight if something is believed to be correct from broad experience and/or has been backed up by peer-reviewed research.
The reason I mention this is that you won't hear much hogwash here like you do on other forums. "It works for me so it must be good" doesn't happen very often. People here are entirely free to share their experience and offer alternative perspectives. If such statements sound like advice, and there's good evidence to the contrary, or risks you need to be aware of, then those will get covered. TFP is not an exclusive club even though our passion might get strong at times

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I hope we can help get your pool as good as it can be
By the way, your layout back in post #14 looks like an inviting oasis to me! There's some great pool construction and landscape experts here too that might have some ideas for you.