What about the saber calling to her is a plot hole? I mean she wasn't going to be a Skywalker either way you slice it. And she wasn't a Solo. It's just a simple matter of the Force calling, her and wanting her to take it. Why did we hear Obi-Wan. Because he spoke to her. Again it's not like they were related. Ezra Bridger heard master Yoda's voice, and I'm pretty sure they aren't related. (Unless she's his granddaughter, but I don't see that working for Obi-Wan. He only ever loved one, and she was killed.) Why are the Jedi putting their faith in a Palpatine? "What greater weapon is there than to turn an enemy to your cause." - Bastila Shan
Again, unexplained stuff isn't a plot hole. But why did she see Kylo? Because they have bond, they are a dyad.
Why was First Order looking for Luke? Snoke explains that in TLJ.
"Darkness rises, and light to meet it. I warned my young apprentice that as he grew stronger, his equal in the light would rise. Skywalker.... I assumed. Wrongly."
Palpatine's plan is to take over a new body, bring the Sith back to power, and reclaim the galaxy. Why didn't he send out ships? He wasn't ready to reveal himself.
The prophecy as the Jedi interpreted it, was wrong. "A prophecy...that misread could have been." And in Rebels, Obi-Wan tells Maul that Luke is the Chosen One. (Also remember that the whole destroy the Sith stuff was tacked on for ROTS. It's never mentioned in TPM or ATOC.) I mean this is the prophecy as stated in Master & Apprentice "A Chosen One shall come, born of no father, and through him will ultimate balance in the Force be restored."