I have opencart v2.2 and I want to edit my navigation bar menu be likes here.

Firstly: Navigation Menu:
1- How to separate between categories like that?
2- How to center the categories words like that?
3- How to change color of the navigation bar?
4- How to do pattern that?
Firstly: Product page:
1- How to change the image with selectio? - because I wanna when select (ex:color) reflect with iamge.
2- How to add note under "add to cart" button in product page?
Thank you.