White will trade pawns on d5 and work on dark squares in the center.
This is a good lecture on the dutch stonewall: http://www.youtube.com/watch?v=ELQ7fNOxHBo
If white was smart enough to play 7 b3, then 8 Ba3 should have been within his reach. The strategic point is to exchange black's dark squares bishop.
First things first, that is to protect the f-pawn:
11. e3 Nd7 12. Nc3 N7f6 13. Nd2 and black has to exchange the knight or get a bad pawn structure.
On the black side is the move 8. ... f4 anti-thematic. Black plays f5 to put pressure on the field e4. Qc2 is in that perspective a normal move, because it focuses on e4 too.
Black could also play 7. ... Na6 8. Ba3 Nb4 9. Qd2 a5 or 7. ... Na6 8. Nc3 Bd7 to create counterplay on the c-line.