You are feeding a good bit, for a new screen. When you are getting some good thick green harvests, you can remove all other filters.
If you cut back your feeding to a cube a day, and stopped the liquid feeding, you could remove everything today. Then after you get thick green, you can up the feeding again. The liquid is what really puts nutrients into the water.
There is no indication for re-installing the skimmer. It does not remove any nutrients at all, so it would not help. But it would remove more food, if you want to buy more food.
No sps will die; they will grow faster.
There is no oversize, or undersize. There is only the correct size, for how much you feed. Use the guideline.
Carbon does the same thing as a skimmer and does it better in regards to taking out the bad things in the water.
GAC removes DOC's... Vitamins, Amino Acids, Carbohydrates, etc. Skimmers do not remove these very well. After you remove them, you'll need to buy and dose more Selcon in order to put them back in.