Lighting questions from a newb...

Ok. I've got my selection narrowed down, I just need some input from the
pros...

I decided I'm going to get the Aqua Medic Ocean Light pendant. I have a
12gal 18"H that I want to be able to keep coral, anemone, etc. First
question is: Would 250W be overkill? On some sites, there's only like a $20
difference between the 150W and the 250W. Besides the higher eletricity
bills, can the 250W hurt anything?

Next question. Since this is going to be my only light source, would I need
to get a 20,000K bulb? I like the look of the 10,000K, but I've read in
several places that those aren't good enough if you want to keep corals.

Another question. How heavy is this unit? I'm contemplating installing a
shelf above my tank to hang it from. This is because I do not want to hang
it all the way from the ceiling.

Ok, last question. What's the difference between the 250W (or 150W) HQI
20,000K XDE and the 250W HQI 20,000K AquaMedic AB bulb?


Thanks for any input!