The purpose of the out parameter encoding
is to give you the Encoding used in the return array of bytes, in case you need it. So you do not have to instantiate the encoding parameter before passing it to the render method or do any extra work with it. Just declare a variable encoding and pass it.
About the second question. Yes, you can use the instance of the report already in use of the report viewer. Use:
I hope this information helps.
the Telerik team