Houston Intercontinental Airport and Staying at the Mariott

I have a few questions re. going to IAH.

I am flying in from Toronto and landing on Friday night, and was looking to stay at the Mariott there (between flights, almost 12h layover). This may be a stupid question, however; Does it connect directly to the airport? Or do I have to walk/subway over to it. I also heard there is an early checkout fee there. My flight is at 10:15am so I would obviously have to checkout early. I plan on calling the hotel about this but has anyone had experience at the Mariott and flying out, or having to pay an early checkout fee?