Where do I find my applications on the server / instance

Every application will be deployed to

/srv/www/APPLICATION_SLUG

where APPLICATION_SLUG is a permalink generated out of the application name. The latest revision of your application be a directory named after the timestamp when it was checked out, symlinked to current - just like Capistrano:

$ ls /srv/www/APP
total 8
lrwxrwxrwx 1 deploy root   42 2010-04-08 18:46 current -> /srv/www/APP/releases/20100408184610
drwxrwxrwx 3 deploy root 4096 2010-04-08 18:46 releases
drwxrwxrwx 7 deploy root 4096 2010-04-08 18:46 shared

The application will be owned and run by the UNIX user deploy.

New versions/releases will be checked out as a separate directory in the releases directory. The current symlink will be updated as part of the deployment.

Please not that /srv/www is bind-mounted to /mnt/srv/www so your applications are really on the /mnt partition.