Re: apparent overheating
The only way that the problem you describe will happen is if there's no coolant flow. If the car overheats at idle this usually means thermostat or fan, but in your case the problem happens only on the freeway, right?, and this means either your radiator is blocked or the water pump has failed.
On the picture, what you circled is not very clear, but it looks like the heater tap or heater valve, which is there to open and close coolant flow inside the cabin (when you select "cold" or "hot"), but this has no weight whatsoever in the cooling system, even if its totally blocked, your cooling system should still work ok, as there are by-pass hoses around the system. Kerrioc was probably referring to the radiator when she said the heater in that post.
There's a simple test you can do that will tell you if this is your problem. Get the car warm and feel the radiator core to see if there are hot and cold patches through the whole area. Remove the fans if you need to. And the car doesn't have to be running. A normal radiator should feel hot to the touch on the inlet side and should get colder gradually as you run your hand towards the bottom near the outlet hose. If you feel cold and hot patches in different places this means it is blocked. If it feels ok, then go after the water pump, which could have worn or loose blades that will give you a shitty or nonexistent water flow. hope this helps. cheers