Nope and nope.
When you are adjusting the RAW data you are not making any changes at all to the file, or at least far less than changing the colour of a file in PS. This is true for any changes to the file, doing it in the RAW converter gives the maximum quality.
I'm not sure but it's possible that this is even more so in this case as the RAW file is decoding the bayer matrix to define the colour and the changes you make to the WB determine how the bayer is interpreted.
When you set a manual WB in camera, either by dialing it in or shooting a test card, all you are doing is telling the camera to input the text value of X kelvin with your RAW file. When you open your raw converter it reads that value and applies it to the picture. As the application is solely within the raw converter anyway it would make no difference at all.
