Is this definitely happening?
if i have btc in gdax, do i get the free coins?
what if i have btc in ledger nano s?
Yes it's happening today! I don't know is gdax supporting the hardfork or not, if not it's better to put your coins in exchanges or another wallet who support the hardfork to get the free coins.
Either kucoin or binance said they would accept all btc forks which is awesome.
I'm holding btc at moment just to get some of this coin, even if it is dodgy... at least it's not bcash.
There you go OP, binance is supporting the hardcap. Send your coins into binance and after the fork you will get the free coins.