I’m a newbie myself (6 months in) but I can answer your second and third question.
I didn’t follow the the official blueprint course but I stumbled upon this channel Make Games With Katie - YouTube that gave me a solid base to build upon.
Then I switched to this DevSquad - YouTube because I found full completed playlists where you sit through the entire journey of making a game with blueprints from A to Z. Still, as I kept learning, I found out that his code was really unoptimized and left a lot of bugs that would drive newbies insane unsolved, but overall you get to learn more about the engine and what does what.
And finally I suggest this guy DevAddict - YouTube who teaches stuff in a fun way.
For your third question I happened to have asked myself the same thing back then and even tried UE5 for a couple of days.
I suggest starting with UE4 nothing really changes after moving to UE5 except for the UI and the new tech (Lumen, Nanite, Chaos…), and the sooner you start learning UE the better all while waiting for the official stable version of UE5.