Awe me happy you love the game so much ^-^
For you to proceed after the keycard you must go to corridor 101, which appears in place of the security room option in corridor 701.
In regards to the mech dragon, the password is on the puzzle you get, and if you don't have Aphrodisiac immunity from eating the stew back in chapter 3. Make sure you didn't eat too much of the special foods the lizard cook made or you will get too hornh to proceed.