I think you'll be ok with the keyholes and pearls. Once the tank is fully stocked you can test to see what your water change frequency and amount should
I stopped using polyshades on my wood projects for the same reason. Very nice job on the stand.
Ditto Bob's suggestion... with the sponge kit it becomes a "660r" or you can buy the kit separately. Penguin 660s have an option to add extra
Parts for the older Oceanic cubes are hard to come by. They haven't been made in years. You may want to get a little moonlight strip and just adhere
I usually use a gravel additive fertilizer and then add liquid fertilizer weekly. I use Fluorish tabs and add Aqueon Aquarium Plant food weekly.