1. Baggage should be checked through but that is up to CO. Make sure they do it when you check in. Remind them the whole Skyteam seamless travel.... yada yada yada

2. you will have to clear immigration/customs and then come back through immigration. The whole process is very quick and painless in CDG.

3. I doubt CO will give you the boarding pass for the AF flight. You have 12 hours and enough time to check in.

Depending on what time you arrive (most likely in the morning), why don't you go into Paris for a few hours and then come back. It is easy. You can read some of the threads about CDG and Paris. I would highly recommend it.