What you want is to create a custom document template. You double-click on the template and you get a new document with the layout, text, and other modifications from the template. Templates can contain AutoText, among other things.

Templates in Microsoft Word

Templates can be distributed or shared and easily accessed by others on the network.
Workgroup Templates in Microsoft Word
Workgroup Templates

To use a template, you do not open it, you use it as the basis for a new document. This is the default behavior if you double-click on a template's icon.