White plays Duras gambit (1.e4 f5) tempo up, well done!
Is 1. Nc3 e5 2. f4 worth playing?

The error is that you lose a pawn. You're claiming that white gets a positional advantage in return but this simply isn't true - in fact black gets the positional advantage of white's weak e1-h4 diagonal.

You propose two lines where black blunders his queen in 3 moves. After Nf3 Be7 and white can't stop the check on h4, is a pawn down with an uncastled king.
Yep, seems totally legit.