The immediate 3. e4 gives Black several good options. Indeed 3. ...Qh4 is again possible, 3. ...e5 should be compared with the theoretical 1. c4 Ktf6 ; 2. Ktc3 e6 ; 3. e4 Ktc6 ; 4. d4 e5 (the difference should favor Black who has options of ...Ktge7) and 3. ...d5 (my usual choice) ; 4. cd ed ; 5. e5 doesn't hit a knight as in 1. c4 Ktf6 ; 2. Ktc3 e6 ; 3. e4 d5 ; 4. cd ed ; 5. e5 Ktfd7 (5. ...d4 is better perhaps) ;
6. d4
As regards Qd3, I believe a move ceases to be dubious once it forced!

Oh, and you were looking for other examples of ...Qh4 : in the Scotch 1. e4 e5 ; 2. Ktf3 Ktc6 ; 3. d4 ed 4. Ktxd4 Qh4 forces White to give up the -e pawn, but after 5. Ktb5 Qxe4+ ; 6. Be2 Kd8, he has rather alarming compensation. Certainly more frightening than 1. d4 e6 ; 2. c4 Ktc6 ; 3. Ktc3 Bb4 ; 4. e4 Qh4 ;
5. Ktf3 Qxe4 ; 6. Be2 d6 Black's Queen is awkwardly placed, but he is solid and has no weaknesses.

As soon as I play a decent standard game with my defence, I'll transcribe it here. Until then further questions/comments are most welcome. 

                                                           UD

Dear Glenn,

  Thanks for your interest. Of course, since there is no theory attached to this defence yet, it is rather difficult to point to a main line.
However, just as in the English Defence, it is only logical that a critical test must be the seizure of the centre, as Black has failed to prevent this with 1. ...Ktf6. Other critical moves are 3. d5 and 3. Ktc3 Bb4 d5 but in my opinion these are less dangerous than against the immediate 1. ...Ktc6.
Actually White's "Nimzo" options are considerably reduced: 4.Qc2 hangs the -d pawn, as does 4. Qb3 and 4. Bg5 is also prevented.
Indeed as you point out, the ...f5 option is very usefull as in the lines 4. e3 f5 and 4. a3 Bxc3 ; 5. bc f5.
I usually meet g3 with ...Rb8 and ...b5 although I haven't investigated this as thoroughly as the rest. As for 4. Ktf3 Ktf6, I consider this to be a perfectly satisfactory Nimzo for Black.
I'll provide more extensive analysis and answer any question you may have soon.

                                                                                regards,
                                                                                       UD

My fighting defence is akin to the following : Nimzo/Bogo/Q's Indians, Two-Knights' Indian,  English Defence, 1. d4 Ktc6 (don't know the name of this one), but I have reasons to prefer it above all these.
Of course, as with The English Defence, Keres Defence and Deferred Dutch, a repertoire containing the French is a prerequisite, but you are avoiding the KIA and other bothersome deviations.

Here is just a sample variation : 
1. d4 e6 ; 2. c4 Ktc6 ; 3. Ktc3 Bb4 ; 4. e4 Qh4! ; 5. Qd3 f5 ; 6. ef Ktxd4!? (6. ...Qxd4) ; 7. fe Ktf6 ; 8. Be3 (anyone brave enough to play 8. ed ?) Ktxe6 ; 9. Ktf3 Qe4 with a mess...


Refutations welcome!