If I do this (and build it to what most of these pics are looking like), will I need a sump also?
I am assuming you realize all a sump is a place to put your heaters, skimmers, bioballs, kalk, Ca, or phosban reactors, etc. A refuge is merely a place that is free from predation and they usually hold LS and macros for nitrate reduction. So it all depends upon how you design your fuge, sump, or fuge/sump as mine is. You don't necessarily need either. You could just have a HOB skimmer on your DT, with heaters also in your DT. So it's all up to you and what you currently have setup, and what you wish to accomplish. That being said, both will help with your water quality in different ways.