1. I would use a sediment filter at the front end after the pressure tank. It is best to plumb a bypass around it in case there is a failure. I like the Pentek Big Blue housings because the elements are large and non-proprietary. There is a wide selection I found an incredible amount of rocks and sand when I flushed my water heater, all accumulated before I put in filtering. I got 3 20x4.5 housings before deciding to get the backwashing iron+sulfur filter. So what I have now is overkill, but that overkill does not bother me. I leave the first housing empty. I have about 17 months since I changed cartridges.
2. Water softener. Not urgent; 8 grains is not so bad. But it is really nice to have. With your low hardness, you will not go through a lot of salt.
3. Spray bottle and a gallon of distilled water (under $1). That might be a year's supply for light use. Use as final spray when washing windows, computer screen, eyeglasses and maybe fancy glassware to prevent sodium and silica spotting. You have 15.1, silica, which is a nice low concentration, but does not wash off, and you have sodium, which washes off. Calcium and Magnesium are hard to wash off, but after the softener, they will be gone. Some people recommend silica as a supplement. I just think that it is not to be feared. Distilled water is also useful for washing off sodium salts after
Your sulfur levels are low, and you probably do not have smells. Your iron levels are very low. Nice.
Are you even sure that you sufficiently disinfected the tap you took your first sample from? I think a top notch careful disinfection might permanently get rid of the coliform.
http://www.moravecwaterwells.com/index.php/maintainance/disinfection-and-testing Adding chlorine would seem to be overkill to me, and then you would want an activated carbon backwashing filter to remove the chlorine.
I would not worry about the sodium. 67 mg per liter before softening should be viewed vs typical 3000 mg sodium or 1500 mg recommended for typical low-sodium diets per day. You might consider a drinking water tap from before the softener.