Regarding the problem in the forum post that you referred, please try the solution provided in the latest post and let us know if this fixes the problem on your side.
As for the new problems, I tried your code with RadControls for ASP.NET AJAX SP1, but I was not able to reproduce the same behavior - see attached screenshots.
Can you please open a support ticket and send us full sample project that can be run locally and reproduces the problems that you report? We will check it and do our best to help.
the Telerik team