Best export options before bringing tracks to Mastering

I am getting ready to export my final mix of 14 songs for a CD and bring it in for mastering. I am currently exporting at 24 bit wav with no dithering (track have been recorded at 24 bit, 44100 sample rate).
 
2 questions are...
    - is there something to do with my optical on the mico preamp that should be considered when exporting. Or, is the export only driven by Sonar. and, is there any other recommendations.
    - (not to do with exporting) is it a bad idea to route my outputs through the small 4 channel berhinger. (so I can have 2 sets of monitors hooked up). Is it affecting my listing through the monitor if the berhinger is kept flat/neutral. (see routing configuration below) 
 
My current configuration
    - Quad core I7, with Windows 7
    - Sonar X2a
    
Routing Information
    Mic/instruments plugged into my Audient Mico Preamp, which is connected via optical to my Focusrite Saffire pro 40, which goes out to my small behringer mixer which goes out to my monitors.