It's been a couple of days since I've seen TLJ and I really think this is more and more what this movie was about. Actually it's more of what the trilogy is about. It's the end of the old and on to the new. It's why they discarded all of the old novels and started their own "Canon". Most of the novels continued Luke, Leia, and Han's story and were fantastic. However, you can only go so far with them.
The Darth Plagueis novel expands on your first question. The rule of two is not an absolute. It is a guide to make the sith as strong as possible. Now what palpatine did was fairly genius. He cultivated apprentices in isolated environments with the goal of seeing the strongest survive. Maul was more of an assassin than anything. Dooku was formerly a fairly powerful Jedi who turned. He was powerful but palpatine basically ensured that he'd fight anakin and the survivor would be his apprentice. He later tried the same between Vader and Luke.
If you ever watch The Clone Wars series they discuss in depth how there can only be one master and one apprentice. Dooku was Sidious's apprentice. However, Dooku took on apprentices on a few occasions and Sidious came down on him big time in the series. Overall Sidious knew that Anakin was the most powerful Jedi and was planning on having him join him and replace Dooku as his apprentice.
Technically, Ren can pretty much just proclaim himself a Sith I guess - it's not like there's a bar exam to pass. Same goes for Rey. But along the lines of the original point, will the Jedi and Sith continue, or will it just be force-users? From a franchise/marketing standpoint, I don't think they let go of the Jedi moniker unless they have something else planned.
Agreed but TLJ really seemed to debunk the “legend” of the Jedi and focus on how it was more a religion then an actual thing. That basically being a force user meant you were either a Jedi or a Sith. Luke told Rey that that was not true. The force was something more then a religion.
I think one problem of the new galaxy the films have created is that we don't actually know the scope of the Rebellion/First Order. My sense is that the they were a smallish rump-Empire that survived the war. They probably had to deal in black market materials, etc, for a good deal of their weapons under whatever treaties they had with the Republic, and the Republic has only just been destroyed, since there's no real gap between VII and VIII.
That's not OT, the novels do a really good job delving into the economics of the empire and republic. Their multiverse is made up of the core worlds and outer rim worlds. In the legends novel, they also go the inner rim, but they're considered very unstable. In general, the empire "colonizes" various planets/systems, especially in the outer rim, and strips them of resources. They cannibalize these planets for natural resources and sometimes labor. Trade embargos are mentioned frequently as well. There is a lot of rich versus poor and political favoritism intertwined.
Going to have to disagree here. This is a character with real-world complexity. Clearly has ambition and motivation, both of which are used by his boss until he turns it against him. And his inner conflict is real enough that when Rey thinks she can turn him back from the path he's on, the audience believes it to - he's not predestined to be the Supreme Leader. I'm not saying where he wound up at the end of the film was unexpected - it isn't - but in the film the character's duality is played so well, it still hits the mark.
