There are a few plot-related questions I didn't quite grasp—mind you, I’m not saying there are inconsistencies; I might have just misunderstood something. If you have answers, please feel free to share.
1) Do we know why Kali’s blood doesn't work for creating the numbered children? Is Eleven, in a sense, "the Chosen One"—simply the most powerful—and the only one (besides Vecna) capable of doing it?
2) If Vecna can use his powers through Will in Season 2 to shape the vines—while Will is connected and transmitting info about the town during his sleep—is he also capable of using those powers through a Demogorgon? After all, it was supposedly him, acting through a Demogorgon, who opened the door to Will’s house in Season 1. If the answer is yes, he could have been incredibly overpowered; for instance, if he had observed Derek being taken into the Abyss in Season 5, Episode 3, he could have retaliated against the group by using his powers through the Demogorgon.
3) How do they navigate the Abyss to reach the tree? They know the tree is likely at the base of the lab, but how do they find their way from the radio station to the lab while inside the Abyss? Do they simply reason that since the lab is further to the right in the real world and the Upside Down, they should just start walking to the right?
4) Why does the white door in Episode 5 specifically lead to Vecna’s memories of Holly rather than Derek? After all, Derek woke up in that field just like Holly did.
5) Sullivan saw Eleven’s letter to Mike in Season 4; doesn't he find it strange—considering Eleven allegedly tried to kill Karen and Ted (who are literally Mike’s parents)?
6) What did Nancy and Mike tell the doctor about what happened to their parents? Why didn't the military interrogate them? Especially since they know Eleven is acquainted with them.