Sending edit from FCP to Color - convert to ProRes first?
 

I have searched these forums and found half-solutions and tantalising clues, but have as yet been unable to find a definitive answer to my questions. I have edited my job in FCP and I now want to grade the job in Color. Do I convert the edit into ProRes before I send to Color, or do I grade in XDCAM EX and then render out in ProRes, and if so do I choose 8 bit or 10 bit?

It easier than you think..
 

If you have picture lock-down and now wish to grade in Color simply select; File, Send to, Color. FCP will send your timeline to Color opening a new document. There is no need to convert at this stage as Color will output which ever Codec you select.
Have you collapsed all you video on to the V1 track? it makes life a bit easier if you elect to do this.

Set up your document in Color by going into setup pane and selecting all the options that match your project, ie if you have shot 1080 by 1920, or whatever ensure you select the settings that match your source video. Select the QT codec that you wish to render to. When finished select send to FCP. A nested sequence of the render is sent to FCP.

hope that helps