I agree about Rey's parentage, but also about Luke's role in the next movies.

I'll be really surprised if his role gets larger than say, Han's in this movie.

At some point it was Luke instead of Han who crossed Rey's path in TFA. They ended up scraping this and started again because they realized very fast that if Luke tagged along, they wanted it to be about Luke and much the same way the audience would be most interested in what Luke was doing, not Rey and Finn. That's when they decided that Luke had fled and the McGuffin became about finding his whereabouts, not old Jedi temples.

As I'm sure they're aware, they'd have the same problem if they bring back Luke at the center of the action in the next movie. In TFA they walked a fine line with Solo (it worked, though many reviewers still thought Ford stole the show from the young cast...), but knew they could risk it as by the end they killed him, he wouldn't return as a Hero of the Resistance, leaving that role to the new trio.

This makes me believe they intend to confine Luke to the role of mentor (maybe even a very reluctant one. I expect Luke to be fairly "broken", more so than Obi-Wan and Yoda) or "quest giver" (they might bring back this idea of having to investigate old Jedi sites.. maybe Rey doing so for Luke now), which will be much easier now after TFA and a first confrontation between Rey and the First Order than it would have been in TFA, with Rey barely discovered by Luke. We'll no doubt see more of him with Rey, but I'm not quite sure he'll agree to return to the Resistance and Leia.

I suspect we might have to wait for the third movie to see a reunion of Leia and Luke - at a time the new heroes have advanced a lot more in their respective arcs, but it's just a hunch.

The dilemma is that unlike Ben and Yoda (at the time of the OT) Luke used to be the hero, and to the audience he still is. It will be delicate to give the audience enough of Luke but without having him steal the show in a way Yoda or Ben couldn't.

Lucas had a bit that problem too, it's one reason why he came up with Qui-Gon's character for TPM. He didn't want Obi-Wan to take the central role before Anakin was ready for them to work as a pair.