That's awesome! I had forgotten about the "music" that cartesian printers make. My first printer used a steel square tube frame that amplified the stepper noise and it would sing a song whenever it printed. My main printer now is a delta that really doesn't make the same kind of sound.
80 C sounds about right for the upper temp limit of a 12v heated bed. For ABS, you'll need at least 100 C. I use a 24V heated bed which can go to 110 C without a problem. Most folks nowadays needing high bed temps are using 24V DC or 120V AC for heated bed triggered by an appropriate AC/DC or DC/DC relay. Trouble with heated bed not staying flat -- is it warping from the heat?
The biggest problem with using stepper motors is that there is no positional feedback. This can be an issue with dual Z steppers where they both need to be 100% in sync for the bed to move correctly. If yours got out of whack, one stepper probably skipped some steps and they got out of sync. Check for binding along the axis that may cause skipping. I don't know which control board Folgertech is using, but typically there is a current adjustment on the each stepper driver. Unless they adjusted the current ahead of time, you may need to make some tweaks here. Driving the steppers at too high or too low of current can also cause skipped steps.
It's unusual for any slicer program to generate gcode that causes a head crash. To see if cura spit out some funky gcode, upload it to
http://gcode.ws (an online gcode simulator) and see if anything looks really unusual about the output.