Developing the white bishop?

Which square should white's white bishop develop to in the following game on move 6?  

I'm having a bad day :)

Both 6.Bc4 and 6.Bb5+ are good, it either depends on your style or mood.  4...c5?! is weak by the way black is practically playing an open Sicilian but without both central pawns and a dangling c5 pawn. 

5...h6? this kind of pseudo-prophylaxis is basically a free move.  Notice how g6 is weakened further.  You can't use this immediately however, but the h6 pawn should tip you off to castle queenside and maybe plan on using it as a hook. 

5.Bb5+! forces him to weaken on the light squares 5...Bd7 6.Bxd7+,Qxd7 (gives black the option of ...Nc6) 7.Ne2! (enables f3, since pawns are on d6 and c5 a Nf3 can't do much though a planned e5 thrust is a plus of the knight being on f3 here)

5...Nd7 6.Nf5,a6 7.Bxd7+,Qxd7 8.Nc3 forces the queen onto a miserable spot (7...Bd7 8.Nxd6) blocking its bishop. 

6.Nc3! if you don't know what to do with the bishop just yet since you're developing, preparing queenside castling, and watching the weak d5 square here. 

7.e5! quite appropriate I look over your game and a lesson I learned from Dvoretsky's School of Chess Excellence 3: Strategy applies here: you need to be prepared a the most appropriate moment (no sooner or later) to cut short the unhurried manoeuvring, and find find and calculate a concrete way to win.  Since you obviously played 5.Nf3 to prepare this push why delay it?  Were you afraid of imaginary counterplay? 

Let's look at as many reasonable variations I can find:

7.e5,d5 8.Bb3,c4 9.Ba4+,Nfd7 10.Qxd5,Be7 11.e6 with a strong initiative and attack. 10...Nc6 11.e6,Qe7 12.0-0,fxe6 13.Qe4,Kf7 14.Bxc6,bxc6 15.Qxc6 black has the bishop pair, but far less activity, no coordiation, unsafe king, plenty of holes, and is down a pawn.  White simply needs to develop his queenside here and get the Rf1 into the game.

7.e5,d5 8.Bb3,Nh7 9.Bxd5 wins a pawn. 

7.e5,dxe5 8.Qxd8+,Kxd8 9.Nxe5,Rh7 10.Nxf7+ black's king is too open while white has material and activity.  White's pawns are all still on the sixth, which is great since he'd had some spare pawn tempi in an endgame whereas the queenside and kingside are weakened.  White's f-pawn here is a candidate passer. 

8.e5! again is good, but not as potent since black can now castle as the bishop is now on e7. 

10.Rxe5??????,Qxd1+ 11.Re1,Qd6 and black wins.

10.Nxe5,Qxd1 11.Rxd1 and the pawn distribution is symmetrical, but since this is an open center you have a clear advantage due to your pawns remaining at home, though maybe black being on move brings it down to a slight advantage for you.  11...Bf5 doesn't look easy to deal with however:

12.Nc3!,Bxc2 13.Re1,Bd8 14.Bf4,a6 15.a4 is one possible line where white's activity gives him compensation for the pawn.

16.a3?? is bad, notice that the center is open!  This should tip you off to go for activity, initiative, and piece play.  16...Rad8! seizes the initiative. 17.Qe2,Rfe8 18.Bxc6,Qxc6 19.Nc3 you are not only down a pawn, but having took this long to complete development black already has a big advantage with his rook, bishop, and queen placements that more that compensate for his structural damage.

16.g3 remains equal, though your king isn't too safe after liquidating your kingside pawns.

9.e5!? is still a good move, but here black gets queens off and at this point since black is castled it's better simply continuing with development, then embark on an attack.

20...Nxf2 21.Kxf2,c4+ 22.Kf3,Ne5+ 23.Bxe5,Qc6+ 24.Ne4,Bxe5 25.Kf2,Qxe4 and white is toast.

25.Qf5?? was black's fatal blunder, not only is black's king weak and h6 enables pieces to point there provoking further weaknesses (g6 is forced after Qe4) but now his rooks are totally inactive, yours dominate the center, and you have a bishop without a counterpart (obviously a darksquared bishop isn't going to parry threats along a lightsquare complex).

26...g6 27.g3! and black has nothing anyway. 

In my new thread on the Caro Kahn defence I can't develop to Bd4 or Bd5! Bd3 looks OK though... I mean it strikes down the long diagional into the King's fortress... and isn't that the ultimate point ?! 

Looking at the OP again, I'm thinking my move  13. Be2 was rather pointless. I mean the N is already defended by the Queen, and I could develop the N on b1 to provide extra protection if I want to move the Q into attack.