Just a couple of observations as I pass through.
*The alcohol will not stay in your system for long. Any connection that water will not seep through, alcohol may. It can pass through PVC and other plastics and eats others.
*Your pump may suffer, as they are without bearings, they depend somewhat on the surface tension of the water to act as bearings for the impeller. A pump will pump it.
*While pure alcohol is quite flammable, mixing with water stops this immediately. Of course, I wouldn't open a reservior with a large airpocket in it whilst smoking--just incase. It's not the fluid but the vapor that burns.
*Windshield (windscreen) washer fluid is fine to use in a small mix, it's already mixed to begin with. The alcohol will leave the system, but that system will be quite sterile for some time afterward unless you continue to add water. It does stop algae, but will do nothing for corrosion protection, so no metal mixing! It contains a small ammount of detergents, so again, it may do damage to your pump in large ratio mixes (no surface tension).
It is poisonous, so keep that in mind.
I used to run it (wwf mix), but since my sytem is all copper based, and sealed well, I just switched to double distilled water instead.