As you've discovered, the filling in forms method strips many Word editing options from a document. In addition to those you've mentioned, spell check will not work.

1. Do not use legacy formfields for this.
2. Use plain text or rich text content controls instead.
3. Use restrict editing > No changes > with exceptions. The area you want to be edited is an exception, as are the plain or rich text content controls on the first page.
4. To repeat data in your headers, you can use a StyleRef Field, which, in my experience, is more responsive than a Ref field when used in a header or footer.

You could use Mapped Content Controls instead of a StyleRef field. These are very useful and you should learn about them even if you do not need them for this project. The Document Properties list under Quick Parts are built-in mapped content controls.

• Repeating Data Using Document Properties Content Controls and Other Mapped Content Controls
• Mapped Content Controls by Greg Maxey, MVP
• Custom Content Control Insert Dialog (makes any inserted CC mapped by default)