To be honest, I dont know why you would try to cram 50 to 70 lbs of live rock into a ten gallon tank. Please note that I am not trying to be mean or agressive, but if your goal is to keep what sounds like a pair of mandarins, you should stop. I have never housed a mandarin, but i know that they are a peaceful fish, unless there is another of the same species present in the tank. A pair, especially in a 10 gallon, is a bad idea. As for a 10g with 50 to 70 pounds of live rock, why not just put that into a 30g or bigger which would look more appropriate. Plus, if you end up trying to fill a 10g with 50 or so pounds of live rock rubble, I dont know how much space is going to be left in the tank or between the pieces for the fish to swim around in. The minimum space requirement for this fish is 30 gallons, not just because of the population of copepods needed for this species, but also because this fish needs that kind of space.
As for the lighting, whether you want lowlight corals or something more demanding, I would rethink the 1x40 watt. trust me, eventually you will regret it. Instead, I would recommend you go with the Coralife 1x96 watt ===>
http://www.marinedepot.com/md_viewItem. ... ct=ES53101 . There are people on this site that use it and like it. You can easily find it for around $80-$85. The other fixture that I would recommend is the dual Current Satellite 2x40 watt ===>
http://www.marinedepot.com/md_viewItem. ... ct=CU01012 . This is the fixture that I use on my 16g, and i like it. I do plan on bumping up my lighting by buiding a canopy over my tank and adding a third fixture, though. Note with all the current usa fixtures that it is difficult to find a fish store that sells the replacement bulbs, and when you do find them in fish stores, they are expensive. But Ive replaced both my bulbs through Drsfostersmith.com for $41 shipped to my house.
Hope I have been of some help to you, good luck!