Dan is right about cloning report defintions for different folders, it is not currently supported. Please do open a feature request for that.
As for displaying folder level graphs on one page, we made some changes in the latest release (which is in development right now) to display graphs by folder. The two reports we added functionality like that is network usage report and client session report. The network usage has an option in the report definition to break it down by folder for both the client count and bandwidth graphs. For the client session report we break it down by folder only for the top clients.