Just so you know, if you need to retake it you would have to wait 30 days from the previous test date. Also, for the reading section focus only on reading comprehension questions (answer a question about a given paragraph), none of the other stuff (definitions, incorrect words) is necessary.
For a scoring breakdown, check this file: http://navmedmpte.med.navy.mil/nomi/nami/clinical/astboverview.pdf
Check the other posts and this website also. That has pretty much everything you need to know. If you take a look at all those links and get the basic concepts down, i'd say you're in good shape. Good luck and let us know how it goes.
Hey punk..don't be shady, help him out and send him a link to your most excellent study guide . Unless of course you're wanting to start charging! (It's good enough that you might actually get some cash hint hint)