Bonnie, you'll need what's known as release forms for the key people who are in the film. Anyone who speaks prominently, for sure. It's necessary in order to get Errors & Omissions (E&0) insurance, which broadcasters require.
Crew deal memos are important more in case you get audited by the IRS. I've never needed them for any broadcasters, and I've worked with PBS, HBO, Bravo, IFC and many big international broadcasters.
I should add I'm not an entertainment lawyer, and I highly recommend you consult with one before proceeding.