I would not worry too much about 'losing time away from gaming'. They have been very good about starting on time at 6:30am and even at a walking pace you can be done and have enough time to catch a 9am event and if you jog/run it, you can also very reasonably finish in time to catch an 8am event! (Note: most events don't start earlier than 8-9am)
Heat can be variable. It will always be humid at that time of year so take that into consideration for hydrating pre-race. I can remember a couple of years when the humidity was +90% even that early in the morning. They do have water stations at the first and second mile though and the course is gorgeous but there are a couple of spots (mostly by the zoo) where there isn't much air flow so things can get a little warm.
Going back to the 'lost gaming time' if you are staying at a hotel that is not within walking distance I would highly recommend checking out NIFS. You will run right past them during the first mile from the start, just past the NCAA buildings. They have fantastic showering facilities and a day pass is only $15.