Had one of these systems professionally installed as follows:
well head
-> pressure tank
->Iron/sulphur-removal (carbon media filter)
->water softener
The whole house, including hot water tank was on this except for a single outdoor hose bib.
With the iron removal system, one thing that had to be added after running it for a year: a peroxide treatment tank. This would hold about 25 gallons of hydrogen peroxide and water and the carbon filter would sip from it as it backflushed every night to kill any bacteria. Apparently, there are bacteria that love iron and had formed a mat over the carbon thus negating the filter's action. Anyway, this had to be filled with 8 gallons of 7% peroxide and filled the rest of the way with water about once every 3 or 4 months.
You will want all of the house water to be filtered in this way, since hard water can damage your hot water tank, especially if it contains sulphur and iron. I agree with Goedjn's comment that you should have a sample tested first before jumping into this. The total system isn't usually very cheap and will require regular purchases of salt and hydrogen peroxide (some systems use chlorine bleach for this instead).