Best export to prep for mastering in X2

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.

Hi Skarda,
If you're exporting in the box (from inside Sonar) your preamp won't have any affect on the resultant file. Ask your M.E., but generally I'd just keep it undithered and leave some dynamic room for the mastering engineer to work. I usually don't go much past -12dbfs. Also, if you want to save your ME a little work you could try and keep a consistant peak level on all the songs you send. So if they all are peaking somewhere near -12dbfs it may make his life a bit easier.

Re: the Behringer, any analog device you put in a signal chain will change the sound of the signal. Lots of folks hook up their outputs to some kind of device to control levels and monitoring, but if you do that, generally you probably want to do one of two things:
1. Monitor through the cleanest, most uncolored device you can get (you can throw lots of money at this)
2. Monitor through something that colors the sound in a way you like and then mix down through it (you can similarly throw lots of money at this also).

I think it's safe to say that most folks will say that a Behringer device isn't going to do good things to your sound, but if it doesn't bug you and your results are OK, use what works. The validity of any technique is measured solely by its utility.

Dean