1. Well, most games are played on valkyria.net (just select it after entering multiplayer). Choosing internet means establishing direct connect with another PC. To do this, you have to enter it's IP adress. For a n00b it is smart to wait on valkyria for someone who would like to play with you (just connect and wait about 10-15 minutes).
2. Just post in the topic. The frequency depends on the choice of the players. Most often the games are played once a week. If you want to create game that will be played every week, just start the topic with rules on this board. If want to create game on valkyria, just choose 'new game' button.
3. No?