4. So Is Emo Ren the uncontestant ruler of the FO?
I wouldn't be surprised if Snoke is actually undead and Kylo just killed his avatar/puppet. I don't think he really cared which of Rey or Kylo turned (Kylo has consistently been shown as conflicted until that decisive moment in the throneroom), as they both seem to have similar levels of raw power. As your questions 1 and 3 make clear, we don't really know enough about the First Order to determine whether there may be other leadership elsewhere with a claim (although any that did would have to outfight a very angry Dark Jedi to make good on it!).
5. Did that moment between Rey and Poe tease a possible romance?
Must have missed that bit. To be honest I was perfectly glad to see the back of the psuedo Rey/Finn love interest and don't care to have them try and force another one in.
6. Where and what are the Knights of Ren?
Kylo's probably murdered then all already in his fits of angst. No, but seriously, I'm assuming this is something that JJ will pick up in the next movie although from the flashbacks in both TFA and TLJ they're probably no more than a handful of part-trained Jedi apprentices anyway.
7. Why did Luke make a map to his location if he wanted to be left alone?
He didn't. The partial map from the Imperial archives was to the lost Jedi Temple on Ahch-To, which Leia/others knew was what Luke had been searching for. For both factions it seems finding the missing part of the map was just their best guess at where he might have ended up, and probably no more directed than ANH Leia desperately heading to Tatooine in the hope that Obi-Wan hadn't moved or snuffed it since he'd last pen-palled with Bail Organa.
Overall this movie undermines a lot of previous Star Wars stories by ignoring them or just making them irrelevant. So much that didn't make sense to me. Lukes story is just a total 180 on his character that was built in the OT.
You mean the previous EU Star Wars stories that Disney categorically wrote off in 2014? None of that matters in these movies because they
never happened. Specifically with regards to Luke, we've really no idea what his character has been through in this timeline since RotJ. For all we know he suffered PTSD after the events with Vader and the Emperor!
For me the event at the new Jedi Temple with Kylo shown in the flashback, from multiple perspectives, doesn't seem that far removed from how Luke reacted in the throne room when he realised Vader was considering going after and trying to turn Leia. Suddenly scared, he lashed out. Only this time it's a perception of deep darkness from his nephew, whose training he was already concerned about, and possibly a Force vision or premonition, which led to a
momentary loss of balance.
If that hyperspacer ramming thing is that effective it means that the Death Stars were never a true threat to anyone, you could just take them out with one cruiser.
If an A-wing ramming into the bridge of the Executor was so effective why didn't Poe or someone just do that with the Dreadnought at the start of this movie? One swallow does not a summer make. I'm sure people can come up with any number of reasons why said strategy wouldn't have worked against the Death Star, and failing that you just fall back on the "nobody thought of it before" get-out clause.
Who is Snoke and who are Rey's parents were two things that were implied to be important questions in TFA. And this movie just ignored them both. The reveal of Rey's parentage is a throwaway line that has no lasting effect on the story. I don't care that they are just dead junkers. You don't need famous parents to be important in Star Wars. But TFA made it seem that she has some connection to Luke by guiding her to his lightsaber. It called to her and we are never given an answer as to why.
I thought both Luke and Snoke hinted at where Rey's power comes from, and indirectly, why she was called to the lightsaber. An inherent unconscious balancing act of tension by an unseen force. The Force Awakens. How and why was Qui Gon drawn to Anakin in Phantom Menace?
For Snoke, I agree some more exposition on him and the state of the galaxy would have been nice, but I don't think strictly necessary. The Emperor was almost as vague in the OT, only with the advent of the Prequels did he become more firmly fleshed out (and the timespan between PT and OT is shorter than that between OT and ST). And as I suggested earlier, I don't yet believe Snoke's story is finished - or Rey's parentage, for that matter.
And Rey just continues to be perfect in everything she does. With basically no training she defeats trained warriors easily. And let's remember that has passed from the beginning of TFA to the end of this movie is, what, a month tops.
Rey's skills and their origin were telegraphed quite clearly in TFA: an orphan growing up in practically indentured servitude on a harsh desert planet where you have to be tough to survive. Combat skills from growing up in such a hostile environment. Technical knowledge from dismantling and selling parts from crashed starships, and living in a derelict Imperial walker. Piloting skills gleaned from her scavenged flight sim headset and being one of Ungar Platt's favoured servants. Compare that to Luke: farm boy on a comparatively safe world (the odd Jawa or Tusken Raider aside) who shoots womp rats from his crop-duster in his spare time.
And I don't believe Rey "defeats trained warriors with ease". Sure she beat up some thugs on Jakku, but then later the fight with Kylo was really tough for her despite Kylo's weakened and disadvantaged state (shot by Chewie's bowcaster). It was only when she "used the Force" that she was able to match even that. Then in this film Luke outmatched her easily in their sparring until she cheats and brings out a Lightsaber, and in the throne room scene is tossed about like a leaf by Snoke and then handled one royal guard (if that's still the term) for every three Kylo fought.
And then we have the First Order, which during no part of this movie feel a like a genuine threat to anyone. They're far too incompetent to be a threat. They could have destroyed the Resistance at anytime by sending some ships through hyperspace to intercept them but they dont' even consider that option. Or send their fighters but they don't do that either.
No arguments on this from me, but then the Resistance leadership didn't fare much better either. Obviously Snoke took a leaf out of Vader's book and killed all the competent officers already!