The field is in a special Content Control set so that when someone clicks in it (as to use a hyperlink) the option to update comes up. You can instead insert a TOC using the command near the bottom of the menu. (See screenshot below.) This cuts out the Content Control.
The shading without the Content Control is a user option on shading of fields. It is not set in the document. You are not going to be able to control that.
Generating a Table of Contents - Complex Documents
How to create a table of contents in Microsoft Word by Shauna Kelly
TOC Tips and Tricks