Please help me analyze: Game with opening Reti A07

Hi everybody! This is my first post here so hello! :)

A few weeks ago I did a chess tournament and fall in love again with chess,I hope here I'll find some help to improve my game. So...

Today I played against a friend of mine: I was black...Fritz classified the opening (honestly I didn't know it and I opened using my "head"...) as  Reti Opening: New York and Capablanca Systems A07 (what's that A07?)...do you know where I can read about it? Here is the game...

1.d3 d5

2. g3 e5

3.Nf3 Nc6

4.e4 d4 (I saw here dxe4 was a better idea..)

5.c3 Bg4

6.Be2 Bc5

7.b4 Bb6

8.Qa4 a6 (this was to avoid b5 but seems a huge mistake...Bxf3 was better,right?)

9.Nxe5 Nf6

10.Bxg4 0-0

11. Nxc6 bxc6

12.f3 c5

13.Bf4 c4

14.0-0? (What was a better idea for white?) dxc3+!

15.Kh1 Qxd3

16.Na3 Nxg4

17.fxg4 Qd3xe4

18.Rf3 Qxf3#

At move 8 I think white is better and I hate how he takes that pawn in e5..how to avoid it? Would have been 5...f6 or 5...Qd6 better ideas?

Thank you for the advice! Now let me study a bit more and post an other game :)