Water alone acts as an efficient coolant, but water causes corrosion and over time may damage parts of the engine. Also, it's prone to freezing in winter and damaging the car. So, using coolant/antifreeze with water is better, as it acts as a corrosion inhibitor and lowers the freezing temperature.
Most cars require OAT antifreeze/coolant, although it's best referring to the handbook to make sure. IAT is another type. DON'T mix OAT and IAT.
The colour of the fluid isn't important - it's just a dye to indicate coolant concentration.
The tank may be red from staining from the dyes used, it through aging of the plastic.
I have a 1994 peugeot 306 xsi and have a weird problem with my gauges
When i turn up my interior fan speed, my coolant temp goes up and my fuel gauge
I guess its something electrical but i dont really know