Coolant drain/fill 2002

This is a 4x4 with the rear HVAC. Time to do the above. Whats the best way to drain? Service manual mentions only the radiator drain. About how much coolant will come out this way? On the refill, any air bleed issues? Also, water here is harder than heck. Is the softened water (about 2 grains) in the house OK or do I use distilled or do I worry too much? Any advice is greatly appreciated.