Add more live rock as creep said.
yep, no bio wheels on the filters, good choice.
I have a skimmer rated way high for my 55, I think it was a good choice and you will more than likely get the same opinion from others. You will get all different opinions on skimmers, just research and go with the one you feel comfortable with.
don't do bio balls in the sump for the same reason as the bio wheels on the filter.
Get very good quality test kits! You will thank yourself in the long run.