My flushing solution:
There is a hose / pipe that runs under the engine near the oil pan, timing belt and after-cat oxygen sensor. IIRC the hose is for the heater. I sliced the hose and inserted a Prestone "T" that connects to a garden hose for flushing. It works as a great drain because it is the lowest part of the cooling system.
To flush,
(1) make sure the heater is turned all the way hot.
(2) open the drain in the "T" and let the old coolant empty into a catch pan.
(3) remove the thermostat and reinstall the thermostat housing.
(4) remove the coolant tank cap
(5) attach a garden hose to the "T" and run the hose on moderate pressure. The water will empty out of the top of the coolant tank. When the water is clear, you're done flushing. You do NOT run the engine! The engine should be cold for this process. A hot engine and cold water could potentially cause a metal or gasket failure in the engine.
(6) remove the hose and let the water drain out of the system. Install the cap on the "T" tightly.
(7) re-install the thermostat with a new o-ring.
(8) check the owner's manual for the capacity of the cooling system. Calculate half of the printed capacity and fill that much of the system with 100% anti-freeze. This ensures you will get a 50/50% mix because any fluid remaining in the system will be 100% water after a flush. Top the system off with 100% water. The solution will mix very quickly once the engine is started.
As for anti-freeze, use only phosphate free. Phosphates in the anti-freeze will cause corrosion of the aluminum parts in the engine - there are many. If an anti-freeze container doesn't say phosphate-free, it isn't.
