Your water is slightly acidic and over time will damage metal components of the plumbing system, including copper pipe. Unless you have a totally plastic piping system I would strongly suggest that you treat the water to neutralize the acid. A backwashing calcite filter (acid neutralizing (AN) filter) can be purchased on the internet for $450 to $700 depending on the size (flow capacity). An AN filter, if installed, will also remove virtually all of the oxidized iron (the iron which is red when it comes out of the tap) in your water and may be all you would need for the iron problem. If you still have an iron problem after removing the oxidized iron then you probably also have dissolved iron that a quality softener would remove if installed after the AN filter.
AN filters do raise the hardness a bit--given your mildly acidic water your hardness would probably increase 1-2 grains. Softeners are typically installed when an AN filter is installed. Softeners are also availble from internet suppliers and cost about the same as AN filters.