How can I get an overview of which documents still need to be signed?
In order to get an overview of the status of all (selected) SIGN items, you can run a "Required Signatures" report.
In Reports, click on Create Report Template and select Required Signatures
This report shows which signed documents must be signed and have been signed. This report includes details about all selected items of report type "Sign".
Look at the video on how to create such document: