This is honestly one of the most difficult aspects of effective public policy and why novel viruses elicit such alarm- we don't really know the answer to many of your questions and ultimately policies have to be made based on best guesses given available knowledge. Usually the move is to be risk averse because if you guess wrong its a catastrophe. I would say that based on the available case studies and research done in Japan on the movement of the viral particles in air, the beach is not a significant concern for covid spread. The protesters in some cities were shoulder to shoulder based on images I saw , but mostly were not packed in like sardines in many places. In those places packed in like sardines, I would expect there to be some transmissions occurring. The football games are a non starter for the foreseeable future because there are a million ways of spreading just to get to the seats and while using bathroom etc. Events that attract crowds or create potential for groups of 30-40+ people to end up in the same general vicinity in an enclosed or semi enclosed space are what causes a community's infection rate to explode out of control. Authorities in most areas can handle a slow and steady trickle of cases but the strain of having to surge and suddenly go from 5-10 people in a hospital in some town to 50 or 60 showing up in one weekend, that is when people start dying because they run out of staff / beds/ whatever.
I truly understand that this crap is really frustrating for people and that it often comes off like a bunch of made up hocus pocus. That is in large part what happens with new viruses and I am a strong advocate for the public health officials and politicians being more clear and transparent wit the population about just how uncertain they are about things. Often times they opt for projecting confidence and being sure because they think that they'll look weak if not, but that is more harmful overall at getting the public to buy in and pull together.
