How do I know what plug to pull out? Where is it located, I have heard they are hard to get out. Do I need to torque the heating element, do I need a special torque wrench? I have already purchased the parts but if I don't want to buy the tools to do the work will a GM dealer install the parts for me even though I bought them.
The element goes in the back left side. See the picture below. As for torque, I would just install it and make it tight. The spec is 50 N·m (37 lb ft).
My last question is why does it have to get so cold for the heater to work? At what temperatures does GM recommend warming engine coolant? And the procedure you sent refers to draining and filling engine coolant could you provide the same type of document for that, I've never done it before.