Digital Personnel File (DPF) Issues

Hi,

I have several issues regarding DPF:

1. How can I add documnets manually to DPF (not from P&F process)? There is an "insert element" button at DPF applications, but it is impossible to click on it (it's gray). I'm talking about application ASR_DPF_OVP_APPLICATION with configuration ASR_DPF_OVP_APPLICATION_CFG.
2. Is it possible to show documents in DPF based on authorization object? and is there any kind of authorizations to specific folders?
3. How can I add additional metadata attributes to documents? for example, attribute "validity date" of document.
4. How can I add documents to DPF from applications, other than P&F ? Is there any program/function that we can use from external systems or WD applications or SAP GUI ?

Thanks in advance,

Tal