How does DX10 mode(with fixer) change graphcis processing in FSX

Hello Steve or any other knowledgeable persons,

I am wondering how DX10 mode changes the way FSX processes graphics.

1) My Understanding was that in DX10 mode the majority of FSX graphics go direct to the GPU and it takes some of the pressure off the CPU, but the CPU is still doing FSX work.

2) Does FSX with DX10 Fixer benefit form SLI or Crossfire and if yes by how much?

Regards,

Sebastian