What are some fun things to do in NYC? More on the cheap to free side preferably..?

We are going to stay in Times Square for July 13th- July 17th. We want kid friendly family fun. We are making one of the days to go to Ellis Island and then the State building and Madison Time Square. But does anyone have any other things to go see that won't break the wallet? Street performances, music, festivals, have to see sights? If you know the prices as well or a great place to find tickets cheap for attractions please include those as well! Also how much is parking and cabs or city buses, toll roads, throughout NYC? Everyone's help would be much appreciated! Thanks!!!