1) I think people misjudge Luke's personality quite a bit in Eps IV-VI and VIII. IV-VI Luke is incredibly naive. Even in VI. In The Return of the Jedi Anakin is still driven by the same thing that turned him to the Dark Side in the first place. To control chaos, to control the galaxy against those things he perceives as injustice, by force if necessary. Only with his son joining him would he be able to do what he wanted to accomplish, only with the imminent death of his son does he finally realize the folly, the futile nature of his goal, especially at that point.
That naivety carries Luke into his actions with his nephew. He has the vision of his nephews corruption and thus makes his hesitant decision, only to realize that that decision itself is what fulfilled the vision in the first place. A not uncommon theme.
I think is actions in VIII are fully within character. Nor do I see an issue with a map, pieced together from clues by people trying to find him on both sides.
2) Wracked with the guilt of his own failure he makes yet another naive decision that Jedi and their actions, his actions, will come to ruin. He shuts himself away in a remote place. VIII actually has a recurring theme that Luke incorrectly caries over from ep V. He will only make things worse if he interferes. In V he finds out about his father, he loses a hand, Han is trapped in carbonite, Leia is now slave to Jabba, etc. Finally at the last he decides to intervene and face the decision he made against his Nephew.
3) I highly doubt Luke gets revived in any sense. Force ghost sure, there is plenty of precedence for that. There is also plenty of potential lore to account for some influence of Palpatine to rear its head in IX.
1.) Luke was told that his father was gone, and that there is only Vader now. But he sensed good in him beneath all the darkness, so he willingly let himself get captured, knowing full well he'd be putting himself in a dangerous situation, in order to try to plea to the Anakin he knew was in there somewhere.
And according to his father's own words; "You were right. You were right about me... Tell your sister... you were right..."
Not sure if that's naive, but I don't think it mirrors his actions in TLJ either way.
With Darth Vader, who was mostly evil at that point and had committed many atrocities, Luke chose to try to save him as his first resort, even if it meant putting himself in danger.
With Ben, who was mostly good at that point, Luke's first choice (even if it was only for a moment) was to slaughter his sleeping nephew.
So that's why I don't think it's within Luke's character.
And if he had changed into such a person over the past several decades, they didn't develop him in such a way where this would be believable imo.
2.) It wasn't the map itself that was the problem. The trope of the most powerful character in the series staying away only works if it actually makes sense for them to stay away. Aside from that fact that people tend to learn from past mistakes, it did not make sense for him to think that it would be better for everyone if he left them to fend for themselves against someone as powerful as Snoke. Even less after he recruited a Sith. And especially after Han got killed and Leia and the resistance were pleading with him to help, risking their lives to find him.
I thought that was a ridiculous storyline, and Luke running from his responsibilities, whether it be the Kylo he helped to create, or saving the galaxy when he was (presumably) the only one who could at that point, was yet another disappointing personality trait of his that Rian Johnson came up with.
Even Mark Hammil has expressed his disappointment and confusion about this new version of his character, and when asked why Luke gave up, he said "When I understand, I'll let you know."
He also added “He’s Not My Luke”.
"Even if he had a problem, he would maybe take a year to try and regroup. But if he made a mistake, he would try and right that wrong. So right there we had a fundamental difference."
And that's essentially the issue people have here.
If you not only enjoyed those things, but still considered him the same Luke as before, then that's great. I really wish I could, but I can't.
3.) Yeah, I don't expect Luke to get revived. I suppose they could come up with some story about how he faked his death because he knew Palpatine was watching, and waiting for him to disappear or something. But since Yoda demonstrated that force ghosts can interact with reality, I'm expecting to see something like that from Luke. Not sure about Palpatine considering he had an interest in things of that nature, and his master knew how to cheat death.
It could also be that his involvement in IX is very indirect, but I hope he makes an actual appearance somehow.