Welcome to the forums. We'll do a lot of marketing this summer, but word of mouth is very valuable to us - so tell all your friends.
You may be happy to hear that we will not be doing any monthly fees. However, there may be some additional downloadable content like new quests and other small bonuses that you can purchase either with actual money or achievement points gained in-game. These additions will be completely optional and we'll still be supporting the one-time payers with the regular patches and some content additions free of charge. We'll probably do a couple community events with game cash/achievement points as prizes as well, so if you want all the new content, you will have ways to get it regardless of your financial situation.