I made some progress with my questions.
If you swipe from the right to preview your Markdown doc, Editorial syncs to Dropbox
This one requires multiple steps. As far as I can tell, to force-reload the currently viewed doc in Editorial, you have to:
Load a different doc
Pull the file list to refresh it
Then reload the file you original had open, which will now have any new edits from Dropbox
I learned from "Writing On The iPad: Text Automation with Editorial", by Federico Viticci, that if you pull down in the list of files in a Dropbox folder, Editorial refreshes the view.
It doesn't give you any visual clue that it will do this
Also, if it has previously loaded the list of files in a folder, and then you return to that folder, you have to remember to manually pull to refresh the folder, to grab the latest files from Dropbox to avoid possible conflicts with edits from elsewhere.
I would really appreciate any tips on this - as I suspect that otherwise, I'll be spending quite a lot of time resolving conflicts - I edit on both a PC and the iPad a lot...
(Another concern is that I don't notice the conflicts, and just overwrite text by mistake)