The simple answer regarding the skimmer is to get one that is rated for double the volume of your current aquarium (so rated for 150G). There are lots of good reef octopus protein skimmers for this size tank, but which one you get depends on how much space you have and many other factors.
I'm assuming you have LEDs? Those require a little playing around with to get right in my experience. I have the AI Prime and have had to adjust quite a bit to get it right. I'm not sure what system you have exactly so I don't know how to tell you to adjust it. If you are adjusting by color temperature, try setting it at around 15K and see what you think. If you don't like it, adjust up or down in color temp until you like what you see. I have mine set somewhere between 14-18K (I say that because I've tinkered with the individual color bulbs on my LED so I'm not exactly sure what the color temp is anymore). Remember that 10,000K is more like natural sunlight and 20K is actinic (very blue). In the ocean, the light that penetrates the water to the depth of many corals is more blue in coral, hence why I recommend starting around 15K and going from there. Good luck!