Really great info, thanks for posting! Mainly want to second all this for others and say most of it was true for me as well. I'm only a year in, though, so my results aren't as dramatic yet. Your story is pretty motivating, so thanks for that too!
Also want to add that I found the fitness wiki to be a great resource for no-nonsense advice like the above. It's a wiki based on Reddit, but it's a separate website at this point. It does a good job focusing on keeping lifting simple and eating right.
In the spirit of casual conversation, two questions mostly out of pure curiosity: what routine did you start with, and what routine has been your favorite so far?
20 rep squats sounds insane. I just started doing 10-rep with BBB, and that's plenty brutal for me already.
I've done 5/3/1 since I started. Used Beginners for the first year or so, and over the last month or two I've switched to Boring But Big, and I'm planning to mix that with First Set Last. I mostly hate switching things up and prefer just to go and do my lifts without spending too much mental energy on planning, so I'll probably stick with 5/3/1 indefinitely.
Longevity and trying to feel actually healthy/mobile/etc. is really important to me, and one of the main reasons I picked 5/3/1 was the emphasis on slow growth and always maintaining clean form. So, TB sounds like it could be right up my alley as well. I made a note of it in case I ever do need to switch things up for some reason.
Also, just subscribed to the Weightroom community!