Another option for long text inserts is AutoText, either directly inserted or using an AutoText Field link. Automated Boilerplate Using Microsoft Word

One of my favorite methods of referencing is the StyleRef Field.
An even better method, if you are willing to spend the time on it is to have linked Content Controls. Word Content Controls CC⁄V⁄BM & DP Tools Add-in

You may also want to look at: Setting Up Letter Templates