1. I have never found a good use for the Order pane. For me it is worse than useless. I always adjust reading order in the Tags pane. If the Tags pane is not allowing you to change the order something has gone wrong.
2. Hopefully you save your work repeatedly to a new file name - 01filename.pdf, 02filename.pdf, and so on. That is the only way I have found to avoid lots of rework - cause it is very easy for something to go horribly wrong when working with Acrobat Pro.
3. When adding a page, the tags for that page will be added at the end of the tag structure - regardless of where I put the page. I put all the tags of the page to be added in a container tag like <Sect>. Then I just have to move the container tag to its proper place.
I think its quite confusing that the Touch up reading order doesn't have to be the same as the tags order. However,
- Assistive technology, like a screenreader follow the order of the tags and not of the order in the order panel. If you manage the reading order through the Articles panel in InDesign (and have the option "Use for reading order in Tagged PDF" activated) the order of the tags are fine.
- You might check the "real" reading order with the help of the screenreader preview of PAC 2 or with the Acrobat plugin pdfgohtml.
- The only use of the Order panel I know of is the reflow view in Acrobat.