Still can (libraries still exist plus the internet) but finding the online resources gets more and more difficult; the fact the author mentioned youtube videos instead of someone's old-internet style "all about pvc pipes" website [0] or comic sans plumber sites [1] is already telling.

[0] https://tomtilley.net/projects/pvc/

[1] https://www.plbg.com/

(found via https://wiby.me/)

Definitely! My understanding is everything I did has been pretty well established pool maintenance for decades now. I'm sure there are loads of good books on the topic, though I'm a good 45min from the nearest library so it wouldn't have been my first choice.