The cordova library will ONLY be available on the device, which would be when you do an emulate or run on simulator or device.
As far as plugins, you can just add them using the ionic cli, your option #2. But keep in mind they will only work on the actual device and not in the browser, so you should always check first for the cordova and plugin global variable before using the plugin so you dont get errors in your broswer console during development using ionic serve