Great Post Pipedr,
In response to the Leader question, according to AMA-MSC the leader should be on the left side of the lane. This is also where you would ride solo so it makes sense. It is preferrable to stagger subsequent riders for more visability, increased stopping distance (if everyone stays on their side of the lane), and better rider vision. Personally, if I don't ride with more than 2-3 people and we're so spread out it doesn't matter. I like to pass the staggered formations, though...
