I've been in the hot seat twice (I don't remember how far I got exactly, but the first time I got the pins and the hat, and the second time I got the pins, the hat, and the shirt)...
...Anyway, as far as I can tell, here's how you can win-- the scoring is done both by getting the answer in correctly, and getting it in first in time. As far as the fastest finger, the person who gets in a lot of the time didn't even pay attention to the question, and just luckily typed in the right combination really fast.
...I got in both times by being first on the list for the the follow up contestants-- First, you have to get all the answers right. Second, as they are reading the answers, if the answer comes up as a,b, or c, start pressing the correct button as fast as you can consecutively AS SOON as the correct answer is shown. If the correct answer is D, you have to know that when they show a,b, and c (process of elimination)-- start pressing the answer D as soon as they show C, because the clock starts as soon as they show the D answer (if you wait until they show the D answer to press the answer, you waited too long...)
Also, if you have smart kids, make sure they know-- I've never seen a young person in the hot seat (and don't have any kids myself), but I guess they give kids much easier questions then we adults get-- so, when you hear about winners, a lot of them are kids! The last time I was up, an 8 year old had won just the day before!