Is the coolant supposed to be up to the radiator cap, in the upper hose?

Here:

 

I hardly ever open my radiator cap... just fill the overflow tank up to the full mark on the dipstick and check it every so often and add as needed... Let the system add what it needs from the overflow tank. Opening the radiator cap just allows air into the system, that's why unless i am changing the coolent i rarely open it.

 

Yes!

Hold it up and fill it, then you will need to purge the air out using the bleeder. Make sure you keep your reservior filled next time. Now if it is full and never changes then check the return hose and replace, check for bloackage, also replace your radiator cap.