Please let me provide a sample code that re-produce the second problem of "yyyy/W"
here is my simple stupid code:
<ext:DateField ID="dp" runat="server" SelectOnFocus =true Format ="yyyy/W" start
Width="200" EnableKeyEvents="false" Editable ="false" >
Test case, choose 5th Dec 2012
After choose 05/12/2012, the datefield correctly shows 2012/49,
But after run out of focus(onblur event?) the datefield's value is 2012/51, which is currently week.
I will post on the bug log and Thank you so much for your help and looking forward for fixing result.