Poor knowledge of the theory? I am not sure if you need to know any theory
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Reply to A) What happens when I play 4...a5 5.b5 d6 and 6...e5 and then develop like a Najdorf? Also, I can play 3...e6, where 4.dxc5 Bxc5 5.b4 Be7 can lead to a Hedgehog Position.
Reply to B) Again, I will just play 4...e6. I dont see what you have. And regarding your comment about White playing e4, White cannot play that easily because the black knight is already developed to f6. Nbd2 is a really weird move in the Wing Gambit...
Reply to C) 3.d5 leads to Benoni, 3.e3 leads to Colle and 3.g3...I don't know what this is called, but Black's position is okay.
And one more thing. After 1.d4 c5 2.Nf3 cxd4 3.b4 e5 4.a3 (following your moves), I can play 4...d6 again, developing like a Najdorf (Nf6, Be7, Be6, Nbd7, d5 etc)