Make sure you are buying a bulb AND the ballast. Replacement bulbs aren't very expensive, but the ballast to run the light is. You can also buy a "switchable" ballast that lets you run MH for veg and HPS for flower. But I prefer CFL's for veg and HPS AND MH for flower. Somebody on here will point you to a good site to buy a little in your country.

Mircale Grow works for growing pot. Lots of people use it and swear by it. But it contains time-release nutes...in fact, the wrong nute balance all together.

I use Prom Mix, which is a good organic potting soil. I don't add ANY nutes for the first 2 weeks...just SuperThrive. Then, I start feeding with bat guano, which is high nitrogen. Mine is 10-1-1, or something close to that.