Na, come on. I know the documentation is not always great, not always clear, and it needs some testing to figure things out sometimes. But the first two three questions are answered if you read the F1 Help for the field Capacity Check: And the F1 help in the field Mixed Storage describes how it works if you have no HUs. Yes, the "Last Clearing Date" is not described - but I guess this is relatively easy to find out. 
Brgds
Juergen