Yes, I am not sure whether they will keep "miju wants revenge" plot at all. As of now, she is the wronging party in their break-up. But we will see. I hope they will keep her cheerfulness and innocence (it's not as if her earlier innocence was born out of lack of experience to start with - she had a lot of hard knocks and still kept her sunny personality).

Yes, I can't see MW shooting SM. Even if he learned SM is a mole, so what, MW loathes his father, why would he care?

That's a lot of time jumps.