The unit should come with bulbs. If you plan to buy it from Big Al's, just call them to double check before making the order. I placed an order this morning for my light set, called in and found out that it doesn't have a reflector. So I changed the order over the phone. Then called back 20 minutes later and changed the other again. They had no problem doing that for me.
In regards to the space, it looks to be like it just sits on the glass. The other lights that they sell show brackets. Since this one doesn't, I'd assume that it doesn't need them. That may be a question for Big Al's unless someone else here has this light. It looks like a really nice light. If you get it, let me know what you think of it.
The bulb that it comes with is 1/2 10000K (I think) and 1/2 actinic, so you may want to replace it. I literally see new plant growth every day even with the 1/2 actinic bulb. I put the light directly on to the glass hood, but it does come with the brackets if you want to use them. I just use the little stick-on rubber feet for it, it raises the strip about 1/4 inch off the glass. You can find replacement CF bulbs on big al's. The number of led moonlights depends on how long the strip is I think- since I got the 24" one it only has one led (that's enough for a 20 gallon), but my LFS showed me a larger one on their display tank and it had 3 leds. I don't have a pic on the bottom, but I can tell you that the strip has a plastic cover over the bulb that you slide out when you want to replace the bulb. HTH and if you have any other questions PM me and I'll answer when I get back in town on Monday. 
