There's a "quick start" guide available at the Tremorworks website, which includes a table giving HDL 1-60 (rolling higher than HDL 10 is rare; normal human stats cap at 10). It also includes a breakdown of character creation, and an example of skill uses and combat. It's the top link here:
http://tremorworks.com/downloads-section/
And yes, the better your stats, the higher your average, and the more assured you are of succeeding. That is an intentional aspect of the system. However, anyone has the capability to "bump up" certain stats using Energy, and thereby increasing the HDL you roll.
In response to Spike's review...
Combat is intentionally deadly. The system was designed around realism and role-playing, so the objective is to
avoid combat whenever possible. It's not a hack-n-slash system! Second, I wouldn't say the cards are "optional"... they really are an integral part of the game, and help to keep players alive, and help them succeed. Also, the Narrator only receives a small subset of experience as compared to the amount the players earn, to keep things interesting... so it's not that everything balances out and negates itself.