First let me apologize for my ignorance (or rather confusion). I understand bitcoin may split on Aug 1st and that it may result in multiple chains. I have some BTC in gdax wallet and I am unsure if that will mean risk, or losing ownership should the coin split into two (or more?) chains that may end up like ETH/ETC both being valid (despite ETH being the clear winner).
Any advice at a practical level (e.g.. which wallet, what to pay attention to exactly, what not to, when to return funds) is really appreciated. Thank you!
Actually, there is no news whether the split will happen or not so practically, your bitcoins on an exchange is still safe, for now. However, counter measures should be applied, though the split is not yet confirmed, having just a possibility is enough to secure your coins. As proposed by theymos , himself, you should withdraw your coins to a wallet where you control your private key. Avoid online wallet and exchange.