薪資貌似可以比在北美高一倍.....

薪資貌似可以比在北美高一倍?  Ask yourself how and why they should pay you that much.
做全球性業務 - if they are already established, what added value can you bring in.  If not established yet, are you the one to help them to do business globally?
給老板幹活兒幹久了，想自己管人了 - If you are just an employee for years here, why do you think you can become a manager over night?