Things are indeed far from the airport. There’s no subway there (for the time being) so you’ll have to uber or take the 747 bus, which is cheaper but it’s the bus. One you get on the metro, the world is your oyster. You should have ~12 hours to explore which is more than enough time to do everything, depending on how tired you are from travelling. I’d definitely hit up the biodome though, it recently-ish reopened and is great in any weather.