THE COOLANT ITSELF IS CLEAR the red colour is just a dye.
changing ever few years is a good practice, but many put it off due to the nature of the job.
i havent touched mine in a few years.
 
for maintenance the best thing apart from flushing and refilling is to drain some coolant out and add the concentrate straight in without diluting to makeup the amount you drained out, or dilute at a lesser ratio with water, say 25-75, this is another reason to get the toyota red coolant as there will be some left over and you can use that every few years to improve the coolant corrosion properties, without srainign the while coolant out
i have no backup evidence for this, just something i have done a few times before
 
if you want the engine to run cooler get a higher rated pressure/radiator cap rather than diluting the coolant too much. by reducing the amount of coolant concentration your allowing the water to get to the boiling point faster, but also reducing the corrosion properties of the coolant and also allowing water to freeze faster (not that its a problem here in australia)
cheers

The only problem it will cause is if you cooling system hardware is ****, its really only meant for track use though so the engine can run a bit cooler than nrmal but people do it for the sake of having a name branded radiator cap for looks (nothing wrong with that either)
cheers