Yes you need one and your state probably requires it by law with a trailer over 5000#.
My current truck has one built in but I had a Prodigy in previous TV and liked it a lot.
Basically 4 wires: Power, ground, trailer brakes, brake light. Nno idea about plug and play.
2015 Jay Flight 31 RLDS
2015 F250, Reese straightline
Ham Lic: W4TFB