You can deploy them in your cockpit. They can be moved out at anytime. But Installation is basically "Deploying" the item. Once deployed you can Access the Control Panel and you'll be able to lock or unlock all your doors - that you've installed locks, simultaneously rather then doing it individually w/o a control panel.
You can't use SCP if you do not own it or its not assigned to you as commander. At least last time I tried it out =D So password is not really required unless they would let anybody use it who is in the room.