Where is the rotted out wood...near a water source?
Unless you are familiar with this type of work I would consider hiring someone to do this. Unless you have a sturdy and level foundation the entire room could be off.
Some things you need to consider Are they load bearing,what is actual porch made of, is it wood & rotted too?? Here are a bunch of videos just need to watch them then decide which way to do it.https://www.youtube.com/results?search_query=diy+remove+%26+replace+porch+posts
It's a galvanized 3 season patio, completely enclosed, set on top of a concrete pad. I know that some of the surrounding ground needs regraded. Gutters are working appropriately.