Brian:

Label Header Spacer and Label are used when creating a shipping label specification. I do not believe that you can use these with an Invoice specification.

With a Label specification, the Label section has everything and there is no other section

I've never seen the "Label Header Spacer" before but my guess is it's to help manage the gap between label (when using thermal rolls).

Don't know of any way to include a Title heading as you would like.