Did Bei Fong and Tenzin date?

Absolutley,it was revealed in the episode when Amon took over the arena.

Yes.
But as Tenzin put it: "We [him and Lin] had different goals."
So they were growing apart anyway. But then Pema, Tenzin's now wife, confested her love for him. And yeah~

Yes they did. Jinora said' "stay away from my dad's ex-girlfriend!" in the episode where their island was invaded

yes...yes they did

yes they did ! tenzin said it somewhere in the anime ... I'm just curious for how long though ^^