will help you to know if it is the store front or admin
Unfortunately there is not one central place where all css is added. Different modules and even different pages may load their own css style files through getCSSFiles(). I don't think there is a way to say in your module "load this View class after absolutely everything has loaded" so you can use the getCSSFiles() to overwrite all css styles with your own by starting with an empty list.
Removing or changing wrappers is also not so easy. Unless you remove all css so styles do not apply or you re-write these css style rules.
All these wrappers for different sections are in the template files and you will have to overwrite those. Not to mention XC5 heavily relies on js and these wrappers are included in hundreds of js files as references. So removing them will most likely break lots of the functionality.