I have an app written with GWT and GAE where every supported city has its own app.  Clearly this is not the best way to manage the map so I want to merge them all into one app.  Currently my app is at the urls sub1.myapp.com, sub2.myapp.com, sub3.myapp.com, etc, and I want them to be at myapp.com/sub1 ,myapp.com/sub2, etc.  All the supported cities share common code, so  I'm going to put all the that code in one module, and have a different module for each piece of unique code block.  Is this going about it the right way?  How will the different modules interact?  
Also, I currently have JSPs at sub1.myapp.com/listofsomesort and I would like to move these to myapp.com/sub1/listofsomesort.  Is there a simple way to accomplish this?