As long as the project is portable this should work. We have tested btsync and did not experience any troubles. In order to edit it the path needs to be writable. This is mostly the case unless on sdcard, which is also documented on the same page.

As long as the project is portable this should work. We have tested btsync/resilio which is conceptually comparable to dropbox and did not experience any troubles. 

In order to edit files they need to be at a location which is writable for the app. This is mostly the case unless on sdcard, which is also documented on the same page.