We are on muncipal water and have some problems but nothing like you're describing 😲😳

on the hot water heater did you ever service it? IE; drain and remove the sediment that accumulates in the bottom from the hard water? Should be done yearly and is a PITA. I usually do ours every 2-3 years

the faucets etc. would indicate a really bad case of hard water and I might look into why and if there are other causes/solutions
keep us posted