This is confusing stuff, but there's no "deciding" if your coin is a BTC or BCC, the chain split and both exist now if you had a BTC pre-split.
The chains do not talk to each other in any way, so you can spend your BTCs and BCCs independently. So yes, free BCCs were given to everybody with BTCs.
Imagine it as if someone copied the entire history of bitcoin and just renamed it and started running on different nodes. That's basically what happened. If the bitcoin history showed you owned 10 BTC, then the renamed history shows you own 10 BCC.
The chains do not talk to each other in any way, so you can spend your BTCs and BCCs independently. So yes, free BCCs were given to everybody with BTCs.
Imagine it as if someone copied the entire history of bitcoin and just renamed it and started running on different nodes. That's basically what happened. If the bitcoin history showed you owned 10 BTC, then the renamed history shows you own 10 BCC.