How do electric hot water heaters explode and what can be done to prevent that from happening?
Yes, that's a scary article but keep in mind that both safety devices have to fail to have the tank explode. The pressure release valve and the high limit on the thermostat both have to malfunction. Both of them to my knowledge operate at around 200 degrees F. The maximum you can set most water heaters is 150 degrees F but most recommendations are to set them at no higher than 120 degrees F. Also you should check and test the pressure release valve periodically for leaks and operation. 

Replacing the water heater is a relatively easy task. Just make sure it's completely full before turning on the breaker or you could burn out the elements. Also, avoid using those corrugated pipe. Sweat copper tubing all the way. Your steamfitter friend can instruct you on this. Good luck