I remove the access cover in the front of the wheelwell and take a LED light and shine it toward the coolant recovery tank and it usually illuminates the fluid enough so I can determine the amount. The LED light I have is a cheapy Harbor Freight one which is 2 1/2 " by 1 1/2" with a bunch of lights on one side and it has a plastic hook whicih unfolds so I don't drop it into the bottomless pit behind the foglight. You definitely need a nice bright light to make this work.
Not sure why the surge tank would have a line indicating a working level. It should always be full. When the engine heats it displaces the coolant to the overflow tank in the fascia. Upon engine cooling, it ***** the fluid back in. If you only have fluid to that red line, you have a huge air pocket in your cooling system, and if the system is working correctly, that air will be replaced by coolant from the overflow tank. The typical breakdown in this system is when either the cap on the surge tank is bad, the hose from the surge tank to the overflow tank leaks (usually at the hose ****** @ the surge tank cap), or the overflow tank is allowed to dry out, meaning upon engine cooling you will **** in air and not the displaced coolant. Of note about the overflow tank, it is vented, and there will be evaporation. How fast depends on how often you drive and what climate you live in, but the level will go down on it's own. Since the glycol component of the coolant does not evaporate (the water does), when you top off the overflow tank you only need to add water. This will eventually disperse itself into the system as the car is heat cycled. However, if you live in a climate where the car could be exposed to freezing temps, it would be better to add the standard coolant mixture when topping off the overflow tank.
You want a clamp on the line by the cap. It does not come that way.
No. Per my system description above, the surge tank responds to pressure increase as the coolant heats, and above 16 to 17 psi (depending on your cap rating), the lower tank - the overflow tank in the fascia - is a holding reservoir for the coolant until the engine cools and ***** it back into the surge tank / cooling system.
I was too lazy to go out to the garage earlier this AM to actually check my coolant bottles, but I just did and the coolant bottle (top) appears to be completely full and the coolant recovery bottle (in the fascia) is just below the MAX mark.