If you are only doing mushrooms and other low light corals than VHOs should be plenty.

I thought about 500 watts total but I don't understand 55K and all of the other things
K refers to Kelvin.Your higher numbers being more blue and your lower numbers being more yellow to the human eye. Most try to get a combination of both types of bulbs to promote growth as well as make the tank look pleasing with vibrant colors.

I am probably over-simplifying this a great deal (as I tend to do) but I'm sure if you have more specific questions about what you want to accomplish with your lighting someone with more experience will chime in.

HTH, Ken.