most will tell you 1 to 1 1/5 lbs per gallon. but you dont want it sooo packed with rock that you can get any fish in there. I would suggest 1 lb per gall to start. stack it up, move it around if you feel you need more then add. you can also do most of your rock as base rock, then add live rock to seed it. so for a 55 gal do say 30 to 40lbs base rock and then 25 to 30 lbs live rock to make 55 to 60 lbs. it will save you a lot of money
Rubix 200 lbs for a 75 gal is a lot of rock. 100 lbs would be a good start. do 60 lbs base rock and 40 lbs live. then you can always add more if you think you need it.
both of you e-mail me m0m24 at earthlink dot net.
Hutch-it would all depend on what kind of corals you want. for softies, like mushrooms, zos, leathers. a fixture with 265 watts would be good. thats what i have.
check the sell forum for a used one. I think there was one forsale. satelite makes a good one.