One possible addition to part A: when I've hiked with one particular group, the rule is that if you go off the trail for any reason (usually potty stops) you leave your pack at the edge of the trail, on the side you departed from. When the rear leader reaches your pack, they stop and wait for you, thus ensuring that nobody gets left behind. If for some reason you get lost, at least they will know which direction you headed and from what point.

Also, if the front leader reaches a fork in the trail (why can't I stop thinking of Johnny Carson here?) they stop and wait until the next person reaches it, and so on down the line, so that nobody hits the fork and has to make a decision on their own which way to go. For river/stream crossings, same procedure, so that nobody has to cross unassisted in case of a slip. Generally any kind of a crossing is a good place to everyone to stop for a break and wait for the stragglers, help them across, etc.

It sounds like you are being very responsible about ensuring the safety of your group - good for you!