Nope. Dumping vehicle fluids down the drain is actually illegal. Though enforcement is lax, there is a good reason why such law exists.

Coolant tastes 'good' to kids and animals but is very toxic. Coolant has been used by wives to poison their husbands (hinahalo sa drinks).

You can drop them off at the gas station. I'm assuming most of them have facilities to take care of such substances since they are required by law. Even the water they use for carwash/engine wash has to go through filtration.

I'm not sure about coolant turning acidic. But it does lose it's lubricating and anti-corrosive properties when it gets too old. This may be the reason for the corrosion and stuck up water pumps. Not the coolant itself.