I don't know for sure. The ending of such a manga can be quite unpredictable and might not have been revealed yet. You could try discussing it with other fans to get their speculations.
I'm not really sure if they end up together. Different people might have different interpretations. Maybe you can dig deeper into the manga and form your own conclusion.
It really varies. It depends on the plot and the author's style. Sometimes it can be a few chapters, while in other novels, it might stretch over a significant portion.
First, you need to have a unique and funny idea. Then, practice your timing and delivery to make the jokes land. Also, observe other successful comic acts for inspiration.