With well water there's usually no need for carbon block. The size of the debris determines the micron size of the particle filters you should use, and will require a little experimentation on your part. If whatever unit you get has 3 cartridge stages would recommend starting with a 10 micron, followed by a 5, then 1, and see which microns do or do not catch debris. If you put a 1 micron first and your debris is mostly 10 micron sized, then obviously it will stop it from passing but will clog quickly. So to get the most out of your filters figure out what size the debris is.
With particle filter especially it helps when the the unit is clear so you can see the filter inside and have a better idea of when to change em.
For relatively dirty well water a 5 stage unit is a good idea
Spectrapure is imo one of the best units out there, and has an adjustable flow restricter to accommodate some moderation in water pressure, which helps prolong the need for unit maintenance. But with well water, and it's ability to adjust water pressure think BRS units are the best bang for buck as far as getting a decent reliable unit. And if I were you BRS 5 stage is what I'd get
On a kinda separate issue, as far as the iron in water on the rest of the house as well as the rodi unit. May seem expensive. But with virtually no maintenance, no cost to run, and prolonging the life of all the plumbing fixtures throughout the house, a wise investment
https://www.filterwaterdirect.com/products/whole-house-iron-water-filter
