Opinions on glass covers are mixed, although most will say get rid of it. It slows down oxygenation and also gets covered in salt, which prevents light penetration. On the good side, it reduces evaporation so you have to do less top offs.. Of course evaporation is needed tool cool the tank.

Refugium/sump's are easy. Either put a tank or rubbermaid container under your main tank. Hook up an overflow box to your main tank that drops water into the refugium, and then have a pump/powerhead that returns water back to your main tank. Make sure the outlet hose for your pump into your main tank is above the water line. If not, during a poweroutage, the display tank will back up into your fuge and overflow it.

I have a screen in my fuge that seperate it into two different areas. The first area is where the water from the overflow gets dropped. In it I have two different types of macroalgae. The algae absorbs alot of harmful things from the water, including nitrates and heavy metals. In the other section I have live rock without predators. This gives the pods a chance to breed without being eaten. The bigger, free-swimming pods then get sucked up the pump into the main tank and act as a constant food source. You can also put stuff like a heater in here to keep it out of main tank.

Keep the marcro algae away from live rock and free floating, it makes it easy to prune it. the stuff grows like crazy and about every two weeks I throw away a handful. (nutrient export). not only does it keep nitrates from building up in your tank, it also keeps algae from growing in your main tank. You will also want to put a deep sand bed (DSB) in the refugium (and in your display tank if you want). This is a breeding ground for good bacteria and pods, and in my opinion, the best looking bottom for a tank. Just get 3-5 inches of sand and put it on the bottom. Without predators, the LR in your fuge will propogate the sand in no time. In my opinion, buying live sand/miracle mud isn't necessary for a fuge.

Skimmer/filter. If you have enough LR (1-2 pounds per gallon) and keep your fish to a reasonable number, you definitely can get away without any kinda filter. Others will swear by their skimmer, but I've never had one and have no problems maintaining good water quality. In my opinion, instead of spending alot of money on a skimmer, spend it on extra live rock for your fuge and display tank.