Basically a fuge will do a couple of very beneficial things for you, especially when you have it lit and filled with macro algae.
1.) Excess Nutrients are used by the algae
2.) The algae grows and you can feed it to your tangs
3.) You can put your ugly rocks in there and more rocks to help with filtration (biological)
4.) You can put a Deep Sand Bed (DSB) which helps in filtration
5.) You can hide thermometers etc in there
6.) You can run the fuge light opposite of the other tank lights, which will help the algae grow and maintain a steadier alk/ph
8.) You can put reactor chambers in there with your desired media (carbon, phosban etc.)

It's very easy to setup. If your tank is not drilled, you would need an overflow box, a return pump, and lighting for it.
Basically, mine is a thirty gallon long, so mine juts out of the back of my stand. If you looked at the tank from the top, it would be L shaped. I have about 3 feet of space behind my tank (it is in a cubby) and I can crawl through the stand, which is why I have my fuge jutting out. My overflow tube just goes straight into the fuge, and I put my return high up in the water surrounded by rocks as to not get critters stuck in it. I have it up high in the fuge so in case of a siphon break, there is less water that can be pumped into the display. Basically, it will pump the water till it has no water to pump, and in that situation, less water on the floor is better! I have overflowed the top of the tank once, but it was because I was messing around with the overflow box, and the siphon was broken. Being that it was so high up, I barely got any excess on the floor. I can take pics for ya if you want, since our setups are close in size. I would still recommend alot more flow!!!! I grab a powerhead and kinda blow the rocks off once a week to get as much garbage in between the rocks out as possible.