There is nothing you need to do to drive in electric mode. If the battery has sufficient charge, you will be in electric mode. The gas engine will automatically (and seamlessly) kick in when and if it needs to. There is no manual control of this.
There is no chirp for the locks. You can set it to briefly sound the horn when you lock it or you can have it flash the lights with no noise. I have mine set to make no sound when I lock it, but if I hit the lock button a second time it will honk the horn. I like this option because it doesn't make noise most of the time, but if I want to confirm that it really locked, I can hit the button twice and hear the horn to confirm. I like this a lot better than the Sienna's chirp.
Ordered 9/19/16 -- Built 10/7/16 -- Delivered 10/27/16:
2017 Pacifica Limited - Molten Silver/Mocha
8 Pax - Vac - SafetyTec - UConnect Theater & Sound
20" Wheels - Tow - KeySense - Splash Guards