mechanical filtration is not even recommended to reef tanks. they become nitrate factories and compete with the tank itself. unless you clean the filter like twice a week.
Basically a sump is a place for you heater, skimmer, and fuge. with a sump, your tank water level always stays the same. wen water evaporates, your sump level goes down not your tank so you add top off water to the sump. another benefit is that a sump adds volume to your tank. the bigger the water volume, the easier
you dont have to drill your tank but its much better if you do.
a fuge is basically a refuge for your pod which would otherwise be gobbled up by your fish i your display tank. fuge also has micro algae which consumes nitrates