Im like you. I love the designing and plumbing. Sitting back and watching everything function as planned. Kinda like planting a garden. A frag tank could be worth considering. Always frags to be made and takin care of. I spend more time at the frag tank than my displays.
The CSS are pretty good skimmers for the money. If you are running them in sump you cant go wrong. But as a hang on I would not recomend them. They tend to over flow unexpectidly and the o rings leak some times. Aqua c make great hang on skimmers.
I dont recommend eggcrate over tanks, especially with halides. Directly under the bulbs is fine but the farther out the light is greatly reduced as compared to no top. Some kind of canopy would be a better choice.
Im sure you have heard but a wallpaper blade/scraper is the best tool ever for caked coraline. Just watch it in the corners as itll scrape your caulk out of the corners.