Can I set up a master project on my desktop and have sub projects in various folders under a single site on SharePoint?
Answer: The problem with Master projects is that Project will not allow you to connect the Master to sub-projects on SharePoint. To work around this, you can check out the sub-projects to you local drafts folder (My Documents > SharePoint Drafts) then connect the Master project to the local version of the file. When you’re done updating, simply check the files back into SharePoint to save any updates.
Answer: You can do this with Project Pro, Project Publisher, or Project Server, however there are some differences in level of detail. Starting with the most basic Project Pro sync, you can get assignments (SharePoint Assigned To field) but not assignment work, only task work. So if you have two resources assigned to a task the task in SharePoint will show both names in the Assigned To field, but the work will be the total work for the task. Working in the other direction, any updates to the task by either resource (% complete, actual work, actual finish) will update the overall task, not the assignment,
Project Publisher allows you to use Assignmnet based publishing, which allows updates at the assignment level for each resource, rather than the task level.
Project Publisher is an Project 2010 (desktop) add-on that must be purchased for $150. It can be used with Pro or Standard edition. You can purchase Publisher at here.