Use character styles to format your fields.

"Is there a way to fix the text position in a form so the data entered later doesn't shift the layout on the form?"

You can put the field in a fixed dimension table cell or a frame. The frame insert button is one of the legacy buttons. I seldom use frames. A frame is sort of like a text box and is very old Word technology. With some form fields, you can also limit the amount of text that can be typed in.


See Please Fill Out This Form - Creating a Form

I assume you are talking about Microsoft Word 2010 Bible by Herb Tyson. It is an excellent book but no book can tell you everything about Word. It would take up a bookshelf and a half.

There are three different kinds of form fields. The new ones are called content controls. The old ones are called legacy form fields. The programming ones are called ActiveX. Do not use ActiveX unless you need them for programming. Do not mix legacy form fields (protected documents) with content controls unless you know what you are doing. Mixing these is not for beginners.

I started a page on forms and never finished it. However the links on in are useful.
Making Forms with Microsoft Word