# add your ssh_key to remote
cat ~/.ssh/id_rsa.pub | ssh user@host 'cat >> .ssh/authorized_keys'

# run commands automatically after doing ssh login
ssh user@host -t "cd /data/var/www/stage/; bash --login"

# create an alias for some command. Add this to your ~/.bash_profile
alias ssh_stage='ssh -i ~/path/to/key.pem user@host -t "cd /data/var/www/stage/; bash --login"'