1) For example what hands to cbet and check back as standard, how to adjust to villains tendencies just by looking at some stats. How would you learn em? well, watch some good people play or training videos made by good coaches.
2) 2k+ is KOTH so it's not that difficult, also over time you get to know who are willing to play and who are not.. for example I used to just note ppl who don't give action so I wouldn't have to join them again other times. In mornings there are times where I don't get any action even if I try, unless I want to play the very top players at 5k+.
3) What exactly do you want to know? Zoom HU at higher stakes is pretty much the same as playing 1 opponent anyways as they usually run with very few players. On lower limit zoom games however I guess you just can't exploit people as hard because your opponent keeps changing. I think if you want to improve then normal tables might be a better choice.
4) In the beginning I think raskolnikovs/gordons videos helped me out the most. They taught me the "basics" and also to think simple. Right now I would say sauces and krabs HU videos on runitonce are the most beneficial.
5) Nope
Awesome, good to hear the stuff I write is being read 
it's not as big of an adrenaline rush as it was when I first shot 5k but it still is fun.
by the bosses I mean the ones that play there but not at 2k for example kanu, ike, 26081985, sauce, KPR16, raulgonzalez, donthnrmepls and such 
