sounds like the water pump went possible blown head gasket
Check the upper and lower radiator hoses at the engine. They have a tendency to expand and split.
If your heater core is LEAKING engine coolant so that your engine coolant level drops too low or the engine coolant is lost completely and causes your engine to overheat then your engine can be damaged beside the mess the leaking coolant makes inside your vehicle ( you might be able to just temporarily bypass the heater core so that no engine coolant is flowing through the heater core )
Yes, it controls the coolant flow around the engine block, without coolant the engine would overheat.
A leaking heater core will cause the engine to overheat because the coolant is leaking out.
yes, especially if the leak is causing coolant to leak, you can run out of coolant. then overheat.
cools the engine. without a fan, the car will overheat and the coolant will boil. the fan controls this from happening by cooling the coolant as it passes through the radiator.
you need to add coolant to the coolant resevoir. coolant is antifreeze. if you dont have enough in your car you can overheat and damage your engine.
Bottom of the coolant reservoir.
Could be a worn out waterpump.
The engine is overheating.
If coolant is up to proper level and cooling fans are working - should not overheat
If by water you mean engine coolant, yes. Loss of coolant, antifreeze, is a major cause of overheating.