On the ladder.war2.ru ladder, when you beat a player, if they're ahead of you, you move up halfway to them. So if you're rank 99 and you beat rank 1, you move up to 50.
If you lose a game, there's no penalty, and warbandit's claim that people get names into the top 10 and then retire them isn't really true. Everyone in the top 10 is using their regular account and gets up there automatically by playing and winning in 1s.
Any bnet map counts toward the ladder although it's obviously true that GOW is the most popular map. If you can convince anyone above you to 1s on another BNE then that works fine too for climbing the ladder.