Ask questions about dedicated servers here and we and other users will do our best to answer them. Please also refer to the self-help section for tutorials and answers to the most commonly asked questions.
With 1000 gigs of bandwidth, would I be able to run a 24-slot TF2 server that will be consistently full alongside a 12-slot server that will only have a few players a few hours out of the day without reaching any overages?
Also you might want to make the order form uneditable,
The bandwidth should be plenty for that server configuration. The only people that come close to needing more bandwidth are usually the ones using their VDS's for other purposes, such as file sharing or media streaming.
Editing the price on that page doesn't actually change the cost, that does make for a funny screen shot though. That price is indeed correct and a pretty crazy deal.