I would probably shoot to have a larger sump. In the case of a power failure you want the excess water from your display tanks to be able to run off and not overflow into your basement.

I would switch your skimmer and return sections. Split the overflow water and have one of them go to the macro algae part. I would have this overflow empty into a filter sock on the right hand side of that refugium. Raise that tank so it is the same height as the other. This way, having a power outage, it would not spill onto the floor.
Add a ball valve onto one of your returns so that you could adjust the flow.

I have read mixed reviews on using filter socks. Some people say you have to change them very often (every three days??) or else you will have nitrate issues. What are your thoughts?

Yes 3 days is good. Some people change them every week.
Some people can't be bothered.
Filter socks collect detrius among other solids, and copeopods too. If you don't collect the solids, then they will pile up somewhere and decompose "rot".
If you collect and take them out of the system, then you are doing a nutrient export kind of thing. Less nitrates your system has to handle, less water changes IMHO
All depends on your bioload, how many fish/corals/food you have in your soon to be system.

Are copeopods not a good thing to have? I have a mandarin and have always kept an eye on my tank to ensure I have loads of them for him to eat. I even try and pick them out of the water when I do a water change to ensure I keep as many as possible (a bit OCD I know, but I would die if I knew he was hungry lol).

Filter socks, wouldn't catch very many copeopods compared to how many you have in the system. Your refugium will grow way more than you catch in the sock. And then how many will die when they go through the pump, back into your display. For sure not all of them, but some.
I would not worry about the sock catching too many.
It does not matter how you do nutrient export, many ways available, you just have to do some.

Ok, that makes sense then. Filter socks seem easier to deal with than a sponge of some sort.

Best brand of skimmer to go with?

I have LEDs on my main display and Aquaticlife T5 on my basement tank and so far I am more impressed with the colors under the LEDS but I am still torn between the two. What is the best brand for each(LED and T5)? Thoughts on the PAR38 bulbs?

I think I am going to go with Eheim pumps for the skimmer as from what I have read they have gotten very good reviews.

Yeah, that seems to be popular opinion alright... BUT that's not what I found.

I was using filter socks and found it a real chore to have to change/clean them every 3 or 4 days. Now I have a large sponge that fits in between baffles in my sump, and takes all of 2 min, to squeeze out in the sink and replace every 2 or 3 days,... way less work than the filter socks.

Plus the sponge is better when I am away, too, as it just pushes up on the baffles when dirty to let some water flow by, whereas the socks used to spill over causing some splashing.

And I only need 1 sponge vs about 6 filter socks that I used in rotation. And this single sponge is 10+ years old now, whereas filter socks only last about a 2 years at best (depends on how many used in rotation).

Anyway, your choice, but hope you enjoy filter sock cleaning if you go that route...

You found it easier to clean the sponge rather than the filter sock? Did you find the sponge still collected enough? The filter socks I have seen are very very fine, I would imagine much finer than any sponge.

Yeah, they both collected about the same, although the sponge does not last quite as long as the filter socks did. I had the large 7" X 16" filter socks, so a lot of capacity. Many use the smaller 4" socks, which would plug up really fast in my system (230g). The sponge is 2" X 3" wide X 14" long. My baffles are actually deeper so could accommodate quite a bit larger sponge. So if/when I buy a new one, I would get a bigger one.

With filter socks, you have to put them in bleach for a couple days, then turn them inside out to scrub them clean, and then back in the water with a dechlorizer solution for another day, and then dry. Some do them in the washing machine, but I know my wife would not allow that... Was a real PITA for me.

Sponge is so quick and easy, with just some squeezing and rinsing in the sink. The gunk comes out real fast, and then pop it back into your sump.