Can't help you out on waypoints .... but, check back thru the posts in this thread, and you'll find links to the Operations Manual, charts that show the shape & width pattern of the sonar beam, a pretty cheap place to buy a blank micro SD card/reader (in case you want to capture screenshots), and a whole bunch of other information.
Even so, don't be hesitant to ask any question or add your observations to this thread.
... cp