Hacker News basics?

So I've used Hacker News on and off for a while but there's a questions I have long wondered.

First off, is there a guide/manual or something I should read? May answer it.

Downvoting. Is it limited to only people with good karma? If so, how good?

  • The Hacker News welcome message

    http://ycombinator.com/newswelcome.html

    gives an overview of the community experiment here, summarizing the site guidelines.

    http://ycombinator.com/newsguidelines.html

    The Hacker News FAQ

    http://ycombinator.com/newsfaq.html

    gives some additional details about how Hacker News is administered. The welcome message distills the basic rules into a simple statement: "Essentially there are two rules here: don't post or upvote crap links, and don't be rude or dumb in comment threads."

    The The Unofficial Hacker News FAQ

    http://jacquesmattheij.com/The+Unofficial+HN+FAQ

    by Jacques Mattheij (a high-karma veteran user here) gives his personal answers to questions that are frequently asked about the forum settings and features here.

  • There are Guidelines and an FAQ at the bottom of the page.

    Downvoting limited to high karma, someone said 501 currently and increased periodically in a recent discussion although I have no way to verify.