It is legal to ride two abreast here in Australia. However, I prefer to ride single file. There's not much point riding next to each other with a view to having a chat as wind noise makes it fairly impossible to hear effectively anyway. We can talk when we stop.

I ride as close to the left as is safe and possible, but after having being cut off by left turning vehicles on the arrival at intersections and roundabouts many times, I am going to begin to move further out from the kerb and centre myself more so vehicles can't sneak up and do this suddenly. Some drivers don't calculate the speed a cyclist is travelling very well, and think they have enough time to turn. Some just ignore your presence and turn anyway.

Ride defensively - expect the unexpected - be prepared to be amazed - avoid contact at all costs (the cyclist always loses this one) - stay alive!