Have I got a deal for you! I spent 2 1/2 years trying to get straight information about water filtration and there just isn't any company going to be honest with you. Every one of them sells exactly what you need: it's going to make better tasting coffee, prettier housewives, won't rust, bust, or collect dust. But they won't tell you what's in it. It reaches a point where they won't even tell you if the filter they offer will fit into the canister they offer.
The system they offer you is a water softener. I know because I saw the word "salt". Salt causes heart attacks, so if you buy a water softener, don't drink the water. It's only good for laundry and showers. Oh, and there is no particular reason to pay six grand.
A whole house filter comes in four standard sizes. You may as well get the biggest, 4.5" diameter x 20" long. The only brand I found that will tell you what you are buying is Big Blue. They give full specs, pressure drop, particle size, and so on. The particle size in that filter is either 1 or 5 micron. 5 is adequate for almost all purposes. You would want 1 micron if you have a lot of bacteria in the water. You might want a carbon filter to remove chlorine and other gases.
Hard water mostly affects laundry, and only if you wash with hot water. So don't wash with hot water. Add bluing to the wash water and use less than a normal amount of soap. Add vinegar to the toilet to prevent a ring. Use vinegar for the rinse in your washer.
Hard water usually means magnesium, which is a necessary nutrient, good for heart health. My Big Blue whole house filter stopped most of it, to the point that I can wash the car without leaving white spots all over. If you actually eliminate it from your water, you will need to take pills every day. GE makes an R.O under-sink unit for about 130 bux, eleven gallons per day, and that works just fine for me.