This is Alekhine's defence... and Freddy may not be looking for a quick knockout. He's probably gonna get advantages in other ways [positionally, material etc.... as long as his opponent's demise is long and drawn-out  ]

I don't like the pawn exchange here... the pawns can cramp Black's position. I think usually, Black initiates the exchange

Not so. The advanced pawn may look cramping, but White has a big commitment on his hands if he wants to defend it. (Black threatens …dxe5; dxe5 (Nxe5? Qxd4) Qxd1+, for instance, where the center has completely disintegrated and the White King is insecure.) Exchanging was the right move, keeping the d- and c-pawns intact and letting the f8 Bishop bite on the d6-pawn.

If I were white I would be looking to get my queen on b3 at some point, if only for the nice diagonal a2-g8

I prefer 12.c5 to 12.cxd5

you have swapped one of your active knights for his less active one.

Also, as the proud owner of an isolated d-pawn, you are looking to use your extra space and open lines for attack. Trading off minor pieces – especially such a nice Knight – is the last thing you want to do, since it lessens your attacking chances and makes it easier for Black to target your isolani. I bet that Freddie intentionally left his Queen opposite your Rook, seeing that the discovered attack gave you nothing and expecting you to try to force things.

I concur with Charlie, as you exchange one of his pieces that was on the sidelines when you could have moved the knight say e5 harrassing the Black queen.

If you look at your position you have a lot less central control, you are also forcing the play and your opponent is just sitting back waiting for you to make mistakes.