The article directly addresses your first point. More cyclists on the streets means individual cyclists are safer. There are a couple of factors at work there:

The article directly addresses your first point. More cyclists on the streets means individual cyclists are safer. There are a couple of factors at work there: * More bikes means less cars, and cars are dangerous. Less cars means less danger. * More bikes means car drivers are more used to seeing bikes, more likely to expect and consider bikes, and will take bike traffic more seriously. * More bikes also makes bike-specific infrastructure more attractive to invest in. The city isn't going to build a separate bike path for a single biker, but for a thousand, they might. Countries with the highest bike safety don't have mandatory helmet laws. Of course that's partially because those mandatory helmet laws are simply less necessary there, but also because they've found more effective ways to make bikes safer, while stimulating instead of discouraging bike use.