Depends on which bitcoins you mean. Might be that one bitcoin exists one one address on one chain but the same bitcoin lies on another address on the other chain. Then which bitcoin is the real one being worth $400?

I think to be sure i would have to see if i can only receive coins that are the same on both chains. Then it wouldn't matter to you when one chain loses and your coins are on this chain.

At the end it's not so easy to bet on which chain will win. That is why normally a threshold is implemented. Only when a big amount of nodes switch to the new behaviour then the fork happens. Which pretty much ensures that this new chain will win because it is unlikely that supporters drop the support then suddenly.