Yes, you can assign more than one skill to a CSQ. If you go to Subsystems > ICD > Contact Service Queue, pick/add your CSQ, then make it based on Resource Skills, then hit Next. Once you do that, you will have the ability to add more than one skill group in there.
Note the wording is minimum competence level when you add the skill group in there.
As far as how the script will know, basically it won't so in your example of French and English, it wouldn't work very well. I would suggest two CSQ's and then just set the skills up as you would normally.
Rick