Absolutely, but the same idiots that text while driving and microwave grapes can also buy bikes, so the existence of idiots on bikes cannot be assumed to represent a philosophy for cyclists at large (in your area, anyway). Are these things you see many cyclists doing? Or just things you've seen a cyclist do?
I see the concerns you've listed, and I agree they're not safe. But I know why people choose several of them, even if I personally don't do them. I have headlights and a reflective vest, but if your hobby bike doesn't and you need to get home after dark, you deal. If there's no safe space on the road, or the visibility is too poor, you deal.
Some of the other things you name, I haven't seen and cannot fathom why somebody would do such things. We're probably not from the same country (let alone area) so our cycling infrastructure will be different.
One of them I have done: riding the footpath in the opposing direction. I'm going at low speed so I can brake, but the only risk is of a bad driver being impatient - the same risk a mobility scooter, mailbuggy, skateboarder etc would have. And I do this if a) the road only has one path, and the otherside i would be exposed on the shoulder, or b) when my destination is close on the same side because it makes no sense to cross the road twice within 100m. Both are decisions I make to reduce my exposure to cars.