Is there anyway to replace the default navigation page with an existing page when I create a new navigation element. I need to update some pages to be navigation pages.
Yes, you can create a new page within the finder, then drag it over the desired section in the navigation editor and drop. The page will replace the existing section landing page.
I noticed that managed links have caused page not found errors or the index (1) page coming up after dragging a new page from the finder into the navigation editor to replace the index page. Is a full publish always required to avoid broken or bad links?
Are the broken links in preview mode or are they on the published version of the page?