Welcome to both of you!
As far as your lighting question, it will depend on what type of coral you will eventually want to keep. Softies, many LPS, and even a few SPS do very well under PC, VHO, or T5 lighting (all some form of high output flourscent lighting). Something in the 200-300w range is normal for a 75gal. You just won't get the fastest growth from them. The other main option is Metal Halides. These are the main option if you are going with a SPS dominate tank. Many of your Acropora's need very intense light to grow and color up.
One point of concern about your older freshwater tanks - did you use copper in them. Coral are very sensitive to copper and some say that there is no way to get it out once it has been used in a tank.