If you hit an average of one land in every three top cards, you're going to break even
Indeed, one of the interesting things about Ranger is that you can lock in the 4/3 mode if you want it when your first hit is a non-land just by leaving it on top for round two of the explorations
Whenever you draw a card, each opponent loses 1 life
Right now, control decks seem to be the most common place to find Locations, although I believe in the long run that aggro decks will adapt to use them as well
Blue cards are centered around the mental side of battle knowledge, control, manipulation, and foresight
If there's a cost associated with having a creature attack a player, its controller isn't forced to pay that cost, so it doesn't have to attack that player