Well it was over 10 years between old Shanks and Shanks right now. The new one is much darker now, I think that Grand Line changed him.
Yeah definitely. Becoming a Yonko, seeing the New World, if Uta is actually canon too etc.
I think this is partially why Buggy hides in East Blue and chooses safer/weaker seas like Crocodile and Moria did too.
Mihawk randomly showing up at Baratie still breaks me now too. I still feel he has hidden agendas, maybe related to his island too. Also why he won't duel Shanks anymore.