Need Help for next summer

We are a family of 4 trying to fly from BNA to VCE 6/26/14 return 7/6/14 and having some fun trying to find business class seats on miles.

I have read a lot of the posts and found all in the information so helpful, but I have some questions.

I went to EF and they show if we fly AF from DTW/CDG there are 6 "O" tickets available. Does that mean low milage and can DL book that for me?

When the return opens should I book that day or wait?

Any other tips I would appreciate as we really only take one big trip a year and save the miles, but it is becoming so hard to get it together.

Thanks in advance