Welcome to Android Central! What's your exact model number? Did you get an unlocked version, or did it originally come from a carrier? If the latter, are you using it on a different carrier? A carrier-specific phone has to be on that specific network in order to get the official system update over the air.
As for the excessive heat, you really have to give us more details. We're not The Amazing Kreskin. Hey-ooooooh!