Thinking of starting GFO for phosphate removal

[Tensa]

Hi guys.

A little history:
I started this tank in August of 2017, and I decided my method of nutrient removal at that time was to grow algae in my sump. So instead of making a proper algae turf scrubber, I got some of those white plastic square things from Walmart and roughed them up and put them in my sump. And I set up a light I had lying around in my sump. I was growing and harvesting algae for 4 months until I purchased a pair of potter's angels, and I started getting paranoid about them eating my coral, so I started feeding more. With more feed, the algae and bryopsis in the sump exploded.

I noticed I had a lot of bryopsis growing in the sump which then started growing in the sand bed of the display tank. I attribute the sand bed growth to my poor husbandry habits and nutrients building up in the sand. Around the same time, I was out with the flu and my fish had velvet. My tank got wiped except for one potter's angel who I've treated and is now in a smaller tank awaiting a forever home.

I'm treating my tank with fluconazole and I think the reason my nutrients haven't exploded from the die off of the bryopsis is that there is no fish in the main display tank.

After my fallow period ends at the end of April, I will be re-introducing some fish into the display tank. I've thought about my nutrient export for when that happens and I think I want to try some GFO's this time. (I hope this will help with some brown slimy algae by removing excess silicates as well).

I have a few questions:
1) I notice people that run GFO's seem to run carbon as well. Is there a reason for running carbon with GFO?
2) My understanding is elevated phosphates can be a real killer of corals, but elevated nitrates are not as much of a concern. Is this a correct assumption?
3) What would you suggest I use to help maintain appropriate nitrate levels?
4) Do I need a protein skimmer to use GFO's?
5) Yes, I do not have a protein skimmer... I've read so many conflicting arguments for why you should have one and why not. The reason I did not get one was because some people believe that the organics in the water provide nutrients to the coral. Let me know if you feel differently, I have been looking at potentially getting one if I go the GFO route.
6) If I move away from trying to algae scrub, do you think a tupperware full of miracle mud could help with nitrates?
7) My understanding with GFO's is, I need to purchase a reactor. I will put the GFO in the reactor, maybe put some filter floss in the reactor to prevent any GFO dust from leaving the reactor and that is it?

Long post, if you got to the end you win a *thumbs up*.

Thanks guys!