Big fan of The Walking Dead, Game of Thrones, Sons of Anarchy, Teen Wolf (just check it out, it’s great) and just started watching The Leftovers which I love so far.
As for movies, I’ll probably forget a ton, but here’s a few I love: The Matrix, Lord of the Rings trilogy, Man on Fire, Guardians of the Galaxy, Dark Knight trilogy, Bourne trilogy, The Crow, Training Day, …
Depends from person to person.
Speaking for myself, my girlfriend is by far my best friend, and for me it’s more than enough. I have friends outside of my relationship, but I honestly don’t feel like I would need that or would lack something if I didn’t.