Hoses and radiator- inspect and change only as needed. Typically, OEM Toy hoses last a LONG time. My 10 year old, 200k mile hoses are like new, but the GM radiator sprung a leak and I replaced it with an all metal aftermarket one.

I've heard its bad to use tap water because it has minerals.
I've heard its bad to use distilled water because its more corrosive.
I've used both without apparent problems though. Nowadays I buy the Toyota coolant and mix it with the water they sell for radiators at the parts store (Peak or Prestone I think). I forget what it says on the bottle- demineralized but not distilled or something like that.