Anyhoo, congrats on getting a Nexus 4. Make sure to upgrade it to 4.3 ASAP. I hear it fixes 4.2's bluetooth problems and speeds up the phone in general through various optimizations and TRIM.
Why random chargers can kill your phone is because of poor voltage controls. http://www.righto.com/2012/10/a-dozen-usb-chargers-in-lab-apple-is.html
spikes, noise, voltage sag, regulation (all of which relate to voltage) are what can kill your phone.