I can’t help you with the luggage on NH + AF, but you will have to go through customs (not immigration) in BCN in any case.

When you leave the plane there will be a screen telling you to go to zone “A” or “B” to pick up your luggage. For you (on AF from CDG) it will “A”. And there are screens that tell you the zone for all arriving flights. But if you have a bus gate, they will drop you off directly at the correct zone and you will not be able to see the information for the other zones.

The problem is that you friend might arrive in T2A, B or C. (Iberia uses all 3 terminals.) It’s easy enough to get from T2B to T2A landside and meet someone there (it’s one big building). But to get from T2C to T2B landside he/she will have to leave the building. (There is an interactive map of the airport here. I could not find an English version.)

I would tell your friend to meet you at the far end of terminal 2A (going left after exiting customs). There is an area with a snack bar (I think “Fresh & ready”) and some tables where you can wait. And since it’s almost at the end of the building you cannot miss it.