This was a Critical Mass event, which is why the bicyclists are taking up all of the street as a way to reclaim the streets and protest the lack of safety for riders under usual conditions. It’s not legal, but protests are never useful if they’re fully legal now, are they.
Yes.
Source: stood in a bike lane while drivers deliberately rammed me with their car. Twice.
The bike lane in question has plastic barriers protecting it now. Frankly, that direct action was more successful than the previous decade of activism the “proper” way by showing up to planning meetings and such.