Cole - You can sift through some of the answers here to get a feel for things. Your speed during prime time (5pm to midnight) and the first couple of hours of the free zone will depend on the number of users in your beam. Where I am in Virginia can slow down to 1 to 3 Mbps during prime time and then roll along at 18 to 20 Mbps in the morning.
As has been pointed out, the latency for a geosynchronous satellite can make twitch type games unplayable or at a minimum put you at a serious disadvantage.
I have never had my free zone not start when it was supposed to, but I usually waited until 12:15 to start the big downloads. What I have had happen is start a 3GB update from Microsoft and they decided things were moving to slow and put me on hold until 7am the next morning when I was out of the free zone. Ouch.