Features and usage are summarized on the homepage.
This script will prompt for confirmation before it does anything:
ruby -e "$(curl -fsSL https://gist.github.com/raw/323731/install_homebrew.rb)"
Afterwards, install Xcode.
Indeed, you can. Refer to our complete installation instructions.
Okay then, but please note this installs Homebrew as root and we recommend against that.
curl -LsSf http://github.com/mxcl/homebrew/tarball/master | sudo /usr/bin/tar xvz -C/usr/local --strip 1
Before installing you can browse the Formula folder on GitHub.
After installing, you can use
brew search to find packages or
to browse packages off of a local web server.
The wiki is your friend.
I'm Max Howell and I'm a splendid chap.