Lol good trick about the 100% every day XD but no, you can do it every other or every 3 and he'll be fine. Treating with ES is the same all around, dissolve up 1 tsp per gallon of ES. So since it's a .5 then use .5 teaspoon. The first go around, dissolve it in a small cup and add slowly to his tank over the course of 30-45 minutes of course longer is better
Then the day after next, scoop him out, get water, condition, add salt and acclimate him to the water, gently let him in. I figure you knew this already but just wanted to make sure. if you need me to elaborate on anything just let me know!!
And as for the light, that shouldn't bother him at all. If he was getting direct sunlight then I wouldn't recommend it, darkness has a calming effect so it might help him to have some more darkness than your others. You can always put some paper in front of the tank so he doesn't get as much light
But no, he should be perfectly fine. Pop-eye is not photosensitive like Velvet is which actually uses light to reproduce. Pop-eye is a bacterial infection which causes the swelling.