Unfortunately, the current implementation sets the null value to DateTime.MinValue and this cannot be passed around easily. So for the time being, it would be most convenient if you could set your date time explicitly or set it as default in the corresponding template.
The reason why you do not get any information when clicking the more link is probably because you did not set a SingleNews page via the SingleNewsPage property of the NewsList control. This property should contain the URL to the page which contains the SingleNews control.
Hope this helps. Let us know if you need any further assistance.
the Telerik team