After coolant is added run vehicle to normal operating temperature and re-check coolant level
When the car is cold the thermostat is closed. When the thermostat is closed the coolant does not circulate or get in to the engine block.
The engine could overheat and destroy itself. It's a very bad idea to drive a car with no cooling system.
The engine of your car will heat up.
In brief, you will blow the engine.
No , when the engine is cool
It will seize - due lack of lubrication and coolant (one of the oil's uses)
Coolant will enter the combustion chamber and get into the oil pan. This will cause severe wear of internal engine components very quickly.
The bigger your car, the more coolant you need to put in. The bigger your engine and car, the more coolant you need
If you mean engine coolant is getting into the car, the heater core is leaking coolant causing the coolant level to drop and that causes the engine to over heat.
I'm not positive about your car, or the dash setup, but generally a water light means your low on coolant. If you drive while low on coolant, you run the risk of overheating your engine. Obviously that's not a good thing.
Assuming you still have some form of coolant (water) in your radiator then the coolant will freeze when the weather is cold enough, coolant expands when it freezes, this may cause permanent damage to your engine, such as split pipe's, burst radiator, cracked engine block
It means that you engine is overheating. Check your water coolant level and oil levels. DO NOT continue to drive the car until the problem is resolved, an over hot engine will cease and after that happens you will need a new engine.