Your task will be no easier in Word 2016.

I believe with Content Controls rather than legacy formfields vba will be required. It is possible that you could store than vba in distributed global templates rather than in particular templates. Essentially the vba is going to tell when the user changes the content control. Last I heard, there is no change event for content controls, but I may be out of date.

You might want to, instead, look into a UserForm.
Create a Simple Userform

Learn about styles and ability to limit styles in documents. Use those to control formatting.

Consider using AutoText or other building blocks for your text to be inserted.
Automated Boilerplate Using Microsoft Word

You should be using a template, not a document. This is true whether or not you are using vba. Templates in Microsoft Word

And no, you guessed right, this is not going to be a simple project to create or to implement.