um, no. Yoda and Obi-Wan wanted Luke to kill Vader, and so didn't tell him the truth about who Vader was because that would have made the task more difficult.
It was Luke by himself who came up with the idea of turning Vader and Obi-Wan was skeptical of that plan.
No, all Obi-Wan told him was that he had to confront Vader, I'm sure they both knew that Luke could feel the good in him. It was Luke who took the word confront to mean he had to kill Vader.
nope. Luke says "I can't kill my own father."
Obi-Wan says "then the emperor has already won."
When Luke says there's still good in Vader, Obi-Wan responds that Vader "is more machine now than man, twisted and evil."
And Yoda tells Luke that only a fully trained Jedi with the Force as his ally will CONQUER Vader and his emperor.
Trying to redeem Vader is entirely Luke's idea, Obi-Wan and Yoda are just surprised and happy that it worked.
You're thinking that Yoda and Obi-Wan had the same plans for Luke and I don't think that's the case, Konobi thought Luke was their only hope but Yoda thought otherwise. Still conquer doesn't mean kill and itwas Palpatine who forsaw that Luke would destory him as Vader told Luke,