Filters definitely help keep the dust from settling less frequently! Just need to ask they make it a tad bit smaller - hubby wasn't happy installing them
Filter buy is great! Just measure your current filter snd if they dont have it as an option you can buy a custom fit for a bargain! You can even sign up for reminders as to when you need to purchase your next one!
I live in Northwest Florida and my heating and cooling system has not been running much but when it has I have been satisfied with performance. Real test is this Spring and Summer.