Attaching wainscott paneling over sheetrock

Working on finishing a utility room. The room was roughed in for a sink, toilet, shower stall, and laundry facilities. I am foregoing the shower stall to install additional cabinets. The builder roughed in a floor drain in the cement floor. They also installed a squarish black plastic cap over the hole in the concrete that has the drain pipe. The drain pipe is capped off. I removed the black plastic cap in preparation for filling the hole with cement. I plan on measuring/plotting the location of drain pipe in the event that another owner decides to install the shower. The concrete floor will have a vinyl flooring installed in the near future. People at HD said to just fill it with cement. Before I do this............. Is just filling the hole with cement really a good way to do this? Is there a better way? If it makes a difference the area will have a base cabinet resting on part of it. Thanks, Bryan

1. I have some dampness stains in the corners of my Basement. No water! I tried mild soap and bleach, it really didnt come out. Some of the stains are a rusty color any Ideas, I really want to start painting the walls with Drylok. 2. I was not intending to put insulation up, I am 3/4 underground. Is that ok