Please quote your sources. Many people refuse to answer questions that are unsourced, and it is not uncommon for questions to be deleted if the source is not provided (especially in the cases where the same person posts many questions without ever listing a source).
Also, you should show some effort. What answer(s) did you think were correct? What did you think was wrong? Why? It is only with this information that someone can start to provide you with help.
Call to forward( ) always clears the buffer, thats why it is always said " never flush and forward". if response is already committed before calling to forward you get the IllegalStateException
Call to include( ) doesn't clears the buffer, as include is to get inclusion of response in caller response, so I think it doesn't make any sense if it clears the buffer. for example if we want to include some footer, then we can not clear the buffer.
After forward( ), anything written to response is ignored. But I think control comes back to caller method, But we can not write anything to response. Control flow is normal java. Rules should not change for Servlets and JSP.
Yeah, Its seems correct, If forwarding request is producing any response then we get an exception. Remember : forward means complete handoff of responsibilities to another resource.
I don't understand the last point, What are you asking?
I think the execution control does not return back to the caller servlet.When you call forward ,That means you are forwarding everything to another servlet, and the response is given by that called servlet and not the caller .