Thank you guys! =)
The game was still way off to reach the top 100 (it was at 64% of the necessary yes votes so far) but apparently someone at Valve thought Superku should get the Greenlight already!
I assume this has to do with other factors such as the level of completion (thinking of other survival game prototypes/ early builds, no offense!), maybe the choice of the graphics style (thinking of mostly old school graphics platformers - not saying my game looks nice(r), it doesn't, I'm not an artist, but most games of that genre have the pixel style) and most likely the Greenlight page itself. I'd say take your time with the latter and the trailer video, I wasn't completely happy with it but it was the best I could crank out in 4.5 days.
My Greenlight stats (seems like I'm allowed to publicize that data):
http://www.superku.de/sk_greenlit_stats.jpg@Heel-X: Sadly I cannot say anything about the financial aspects of selling a game on Steam, I don't know it myself yet as I first have to enter quite some data, maybe even found a company/ a trade (not necessary but suggested, will have to ask a lawyer), and then the next step will be signing an NDA.
Rumor has it that you get about 40-60% of the sales (sources on google say that), minus fraud and returns.
There is an FAQ about payment and similar topics on the Steamworks documentation:
https://partner.steamgames.com/documentation/payment_info@Quad: No early access.
I will try to finish it quickly but will take the time it takes so the game (and esp. its final stages) will turn out as I imagined them a few years ago. I guess I will have a beta version ready at the end of the year, then release the game in January-February - maybe sooner, progress currently was pretty good.