I created a simple adapter for displaying hidden properties automatically for certain administrators some time back (code and explanation here), you could try the same approach for adding the asterisk to the required ones. What you would do is change the way that EPiServer.UI.Edit.EditPageControl renders the property names; in theory by altering the name instead of the DisplayEditUI flag in the example. You can check if the property is required by looking at the IsRequired property on the PropertyData object.

Could work :-)