Heu Nico,
I agree with Toni, ditch the biomedia now. Can you put a little compact fluorescent light over it and make it a refugium?
The dead raw prawn is a reliable method of getting the cycle started. What I did with the tank I just set up was to fill the tank, put down my dead sand bed, add some dead base rock, add some sand from my established tank, and add the dead seafood. Worked like a charm. Now I'm going through a smaller cycle with the live rock.
If you want to start thinking about fish, some excellent possibilities are clowns of any species, dottybacks (but some can be very aggressive), cardinalfish, and gobies. Those guys are all kind of small, but you can add a tang when the tank has settled in and you have more experience.
You have got a decent amount of light, and you should be able to keep a variety of soft and stony corals once the tank is ready. Although there are exceptions, I don't find stonies any more fussy than softies. The main difference is that you will have to dose calcium and carbonate for a tank with a lot of stonies. I always recommend Eric Borneman's Aquarium Corals book if you are seriously thinking about keeping them. It takes a lot of the mystery out of the process.