How to handle Black's Bc5 in Bird's Leningrad? I want to learn and play the Bird's Opening, Reverse Leningrad Variation, as White.  I'm having a hard time with some aspects of this opening which keep coming up.  I want to avoid a Stonewall-like setup (d4/e3/f4) as it's boring and doesn't fit my style.  It's a little difficult to find good information on this variation.

One of the more common issues I keep dealing with is Black's ...Bc5 move, either before or after White's castling.  Here are some examples:

Before castling:  1. f4 d5 2. Nf3 e6 3. g3 Bc5 4. Bg2 Nf6 5. d3 O-O and I have to play either e3 or d4 in order to castle, it seems?

After castling:  1.f4 d5 2.g3 e6 3.Nf3 Nf6 4.Bg2 Be7 5.O-O O-O 6.d3 Nc6 7.c3 Bc5+ 8.Kh1 and now I have to deal with the possible ...d4 push.  I know the moves in this example aren't great, for example Black moving the bishop twice, but it just serves as an example of a type of scenario that keeps coming up in my games.  I don't want to allow the ...d4 push.  And the Bc5 can be chased back with b4 push, but it can stay on that diagonal, causing me problems.  And I really don't want to play d4 because I don't like that pawn formation.  (Or is White's d4 a normal part of the Reverse Leningrad variation of the Bird's?)  And also I don't like playing e3 because it seems weak.

I know an e4 push for White is thematic in this opening.  But I often run into situations like this where I don't get a chance for that push, I'm more worried about things like Black's knight going to g4 and joining forces with the Bc5.  And e3 seems like too passive an approach to put a lid on that.  Of course if I get a chance to push h3 I can prevent ...Ng4, but often I have too much to deal with in the centre, and not enough time to get that push in.

I'm not a very highly-rated player, but I study hard, and just want to understand the themes of this variation.  For players who use this variation a lot, how do you deal with Black's moves:  Bc5, d4 and Ng4?  (For Bc5 I don't mind moving Kh1, but should I let that bishop stay around?)

Additionally, do you tend to push both c3 and d3, and put the QN on a3?  (These moves seem to be part of the main line, or at least considered book.)  If so, could someone also help me understand what the knight is doing on a3, anyhow?

There are some key ideas and elements of this opening that I think I'm failing to understand.  Any help on any of these questions would be much appreciated.  (Sorry I didn't embed a chessboard in my post, as I haven't yet learned how to do that -- this is my first post here.)  Thanks!
Objectively ...Bc5 is not a great move in this line, the main reason being the reply d4, especially if you haven't played d3 yet. The stonewall with a Bg2-fianchetto is not the most aggressive set-up, but with one or two extra tempi it is worth going for it and follow-up with c4, Nc3, and then either prepare e4 or Ne5.

In any case, if you choose a move order with 0-0 before d3, your opponent will be less tempted to throw in Bc5. He might be afraid of d2-d4 or e2-e3, have already put a pawn on c5, or played Be7 and not want to lose more tempi.

Assuming he plays Bc5 anyway and you don't want to go d4, you just sidestep with Kh1, keep an eye for ...Ng4 tricks (most often countered by Na3-c2, Qe1, or, well, d4, but sometimes you might want to stop it altogether with h3), and then play the standard Leningrad moves c3 and a4. If Black doesn't react you will grab queenside space with b4, possibly even trapping the bishop. 

If Black goes a7-a5 to stop that, the manoeuvre Na3-c2 covers e3 and add control on b4 and d4. Bc1 is usually developped to d2. Your main plan afterwards should be e2-e4: without a pawn on c5, Black is in danger of getting pawnrolled in the center.

An eventual d5-d4 by Black, without a pawn on c5, is not very frightening. Don't take on d4 unless it wins a pawn. Instead of Nc2, Nc4 becomes another possibility. Same plans: e2-e4 (but don't forget about en passant captures - most often it is no problem because of the sequence: e2-e4 dxe3ep d3-d4 Bc5 moves, Bxe3), Ne5 invasions, h3-g4 expansion followed by Qe1-g3/h4 and possibly f5...

If Bc5 is played before you castle, well, there is always d4. But even without d4, if you are in a hurry to castle, a pawn chain d2-e3 will do. I suppose the most accurate is to continue your Leningrad plans before castling nor touching the central panws: c3, a4, b4 if allowed, Na3-c2, keping your options in the center: either d4, or d2-e3, or d3-e4, depending on Black's set-up. 

Of course, this is all general ideas and many subtleties may happen depending on the precise move order. But the rule of thumb is: don't be afraid of Bc5.

One of those tricks: 

[FEN ""]
1.f4 d5 2.Nf3 Nf6 3.g3 e6 4.Bg2 Nbd7 (4...Bc5 5.d4 (5.c3) (5.e3)) 5.O-O Bc5 6.Kh1 O-O 7.c3 a5 8.a4 c6 9.Na3 Qe7 10.d3 Ng4 (10...e5 11.fe5) 11.Nc2 (11.d4) (11.Qe1 {intending h3 or e4} Ne3? 12.Bxe3 Bxe3 13.d4 {and Na3-c2xe3 is a similar trap}) Nf2 (11...e5 12.fxe5 Ngxe5 13.Nxe5 Nxe5 14.d4) 12.Rxf2 Bxf2 13.e3 {and the Bf2 is trapped}