Hello Ken,
Thanks for the quick reply. The point 1 is working fine I was using setHTML('') and you suggest SetHTML(" "), well not sure what was the problem there at but now this is working for me. For point (2) I want to update you that I am using a license version of cute editor and this is v 6.6.0.0. The point is content area of cute editor is not allow to type text in there. I had faced this problem in ajax model pop-up extender as well. Please investigate it.
Thanks,
Neeraj