Are there any advantages, bonuses or other things i get? Or is it just cheaper and easier to carry on playing once you need to pay for it?
If you buy now, you will get the full version and the paid beta (possibly also some alpha) builds. It is cheaper to buy now though, so I'd recommend doing so. Seeing how far this game got in just a few months is amazing, and things are only going to get better. And no, this isn't some marketing trick. Since I started playing we got FTL, the new universe, the start of the creature system, faction points, and so much more (sitting!).