Overheating

Yes the heat and coolant level are connected! Get a pressure test on the radiator. This will confirm the bad part(s). Some of these small engines do drive the waterpump with the timing belt. DO NOT drive the car low on ant-freeze! If it overheats you can warp the head, then it costs way more cash!

Okay.

When your car overheat, there could be many possible causes.
Among the most common:

- defective thermostat (stuck closed); replace thermostat. One way to check it is by turning on the car with a cold engine, wait until the temperature gauge goes up almost to the middle, and grab the top hose with your hand; you should soon feel the hot coolant exiting the engine. If you don't and your temp gauge keeps going up, suspect a stucked closed thermostat and replace it.

- Low level of coolant/leak; add coolant and fix leak if necessary (check hoses, water pump, radiator, etc)

- defective radiator (clogged); take it to a radiator chop where they can either fix or get you another one.

- Defective water pump; is it leaking? Replace if bad water pump.

- defective fan (don't come one); check for proper fan operation, if fan don't come on when temperature gauge goes beyond the middle, you either have a defective fan or an electrical problem in the fan circuit. To check for proper fan operation, you can also turn on your car and crank the AC all the way up; the fan should come on within 3 minutes. If it doesn't there's a problem.

- internal problem in the engine (water jacket, leaky/blown gasket etc). Do you have coolant in your oil? Try a compression test.

If your level of coolant is normal, you probably don't have a leak; the problem is elsewhere.

I can't tell you how much it will cost because it depends on what the problem is. If it's just a thermostat, it will be pretty cheap (I don't know how much a car shop charges, but a brand new thermostat at an autostore is about $4 or 5.).

The bill will be much scarier if you blew a head gasket after the car overheated. However, if you stopped the car right away when it started overheating, you may not have internal engine damage.

Also, in rare cases, the car actually doesn't overheat but the problem lies within the temperature gauge circuit itself (bad gauge, bad sending unit, etc).