if your talking about the temp. gauge on the dash with the speedometer, gas gauge etc. then its a good thing, when cars run at a temp too hot you can burn the engine up. that's bad.
The thermostat may be stuck open. This is something you may want to replace before winter comes.
probably warming up...if the temperature goes above the average level, then your radiator might be low on water and coolant or the cooling fan is not working..
Your car battery could be running low so what you could do is get jumpleeds and get an other and jumpwire it
Because the alternator will keep your car running as long as its running Type your answer here...
low oil temperature
low on fluid
Yes, it can.
Plugged fuel filter or filters
There are many reasons as to why a Sunfire may be running hot. Most likely the car is running low on coolant, or other fluids.
should be 12.6V same as the rest of the car. it could be as little as 11V when the car is off and battery is running low and as high as 14V with the car running
Provided the heater is of a low wattage it should not affect normal running of the car
Depends on the ambient temperature - need a chart for details
If the battery meter in the car is running low, you probably have a bad alternator or a shorted cell in the battery. There are other possibilities, but these are the most likely. The regulator fuse could be blown, but that usually means a bad alternator.