Ok. I've done some more looking.
1. Do I create a new/different header-catname.htm for each category, edit them with my regular html editor, and then place them in the same photopost directory as header.htm?
2. In the PhotoPost Category Editor should the Header Include File Path be the full server path, relative path, or full url including http etc. including the header-catname.htm as part of the filepath entry?
3. Do I have to turn off intergration with vb3?
4. Do I have to make changes in any vb3 php?