Both choices are great! hamburger vs Text with arrow
the decision should be based on how much do you want user to see them
the better option in my opinion is to go with text with arrow and use hamburger on Mobile
Well there are the NN/G articles on mega-menus.
The decision for menu customization looks like workflow related. Looks like there would be few specialist roles with specialist needs, and those users would just use one or two features, but frequently....