Is it possible to run automatically celery at startup?

You should take a look at http://www.debian-administration.org/article/Making_scripts_run_at_boot_time_with_Debian

In short, with the celeryd script in /etc/init.d:

$ update-rc.d celeryd defaults
Adding system startup for /etc/init.d/celeryd ...
    /etc/rc0.d/K20celeryd -> ../init.d/celeryd
    /etc/rc1.d/K20celeryd -> ../init.d/celeryd
    /etc/rc6.d/K20celeryd -> ../init.d/celeryd
    /etc/rc2.d/S20celeryd -> ../init.d/celeryd
    /etc/rc3.d/S20celeryd -> ../init.d/celeryd
    /etc/rc4.d/S20celeryd -> ../init.d/celeryd
    /etc/rc5.d/S20celeryd -> ../init.d/celeryd