What type of lighting you use all depends on what you want to keep in the tank. If you go with mh, you can put almost anything you wanted. I would go with one mh for every 2 feet of tank length. Also you might want to supplement with vho or pc actinics. 250watt 10k bulbs would be a good all around choice, unless you are going to do clams and sps. 250 would still work fine.
I don't have a chiller,and I run 250watt mhs, and 4 96 pcs on my 135gal. I have 2 cooling fans installed in the hood. My temp is steady between 79- 81 degrees. During the summer, when the lights are on, I blow a fan at the front of the tank and leave the canopy door a little opened. You probably would be fine without a chiller as long as you don't live in a warm climate, and have extra fans on the hot days.