Regarding 3. The shortest distance between two points when sailing rarely is a straight line. For example, if you are in the UK and want to sail to the caribbean you should sail down the portuguese coast, then sail to the Madeira archipelago, wait there for the trade winds to start (sometime in October or November) and only then cross the atlantic (there are variations on this theme but you get the idea). This is because it is much harder and unconfortable to sail close to the wind (that is at a small angle to the wind, say 45 degrees) than it is to sail downwind (with the wind behind you) or reaching (with the wind from the side of the boat). This is still true to this day and it is interesting to see that we still do the same routes today.