Eric uses Mercurial (hg) for managing its code.
Assuming you have Mercurial installed, the following command in a terminal will fetch the most recent code for you:
hg clone http://die-offenbachs.homelinux.org:48888/hg/eric
The code for the various eric versions is kept in a branch per version. After you got the eric code you should switch to the desired branch and run the 'compileUiFiles.py' script in order to convert the forms files (*.ui) to valid Python code.
Stable and snapshot releases of eric are available at the eric download page
In order to get the code of the various plugins, enter the following command in a terminal:
hg clone http://die-offenbachs.homelinux.org:48888/hg/ericplugins/<path of the plugin>
To see the available plugin paths please follow the link below to the eric repositories.
See the full code via a Web interface.