The background parsing is exactly the same as the functionality demonstrated in the Editing Source Files tutorial (of the Getting Started... tutorial set), which means that a number of editor features are enabled to assist with programmer productivity, including:
When focus is on a copybook, the Eclipse window's title bar shows the location of the file and the program currently associated with it.
A trail at the top of the editor indicates which program and copybooks are currently in context - click (Toggle Context Breadcrumbs) on the Eclipse toolbar and use the drop-down list to view and open the dependent copybooks.
The tools available are the same whether you are editing source locally or on the host.
Remember that you are editing a program that resides on the mainframe, and so your changes may affect other users.