There are official instructions on how to install Debian on http://wiki.debian.org/DebianOnFreeRunner, and the announcement.
Previous, partly now outdated information on how to install Debian manually has been moved to Manual Debian.
To make suspend available you have to install apmd:
apt-get install apmd
After that you can suspend your phone with:
apm -s
and make it wake up again with pressing the power button.