Rico,
You are paying for the finished game plus updates for the duration of your subscription to drengin.net and for the enjoyment of testing the beta builds and influencing the final shape of the game.
I don't know of any FAQs but the encyclopedia (left button at the top of this forum screen) is, in my opinion, much better. It includes descriptions of the concepts of the game, a rough draft of the user document, descriptions of the computer players, and much more, but especially the conditions you face at the start of the game (including a hint of what you must do to win the game). You can also check out the screen shots (right button at the top of this forum screen) to get an idea of what the game's graphics look like.
I am enjoying this beta immensely, and I take a rather perverse pleasure in being able to gather objective documentation that helps the StarDock people understand and track down the more dificult to define bugs/deficiencies/concept problems/etc. in the game.
If you like the concept of turn based strategy games GalCiv is a sure thing. So why not get in on the fun now?
Cheers,