You are right, #7 is not addressed in the comment regarding 50 cal machine guns.
I don’t sail so I don’t know much about radar, and we are talking now of 2 different kinds of craft, commercial and yachting.
Thinking of commercial craft, is it unreasonable to expect the radar screen to be manned at all times? Are there automatic alarms that could be in place?
I don’t know the answer to these questions.
I would guess that surface ships commercial radars would have trouble picking up small boat craft against the water which can act as interference. But I dont have one myself, or a boat. If I had one I wouldnt be near that coast without a US military escort, at least the US Coast guard.