I want to dance through an entire song uninterrupted. Can I turn off Freestyle?

You sure can! From the Main Menu, Go to Options --> Gameplay Options to toggle Freestyle on/off. This will turn off the freestyle sections, and instead allow you to dance to more choreography.

Note that only Dance Central 2 songs and subsequent DLC can have Freestyle turned off. When you play songs imported from the original Dance Central or legacy downloadable content, Freestyle mode will still play, even if you have it turned off.