Concerning the holes from the missing compass/instruments...
I removed a broken bulkhead mounted
compass in the
cockpit on one of my
boats, and had a similar hole left over. I bought a
deck access plate. They come in all sizes, and was a breeze to install. The ugly hole was replaced with a nice looking cover, with a removable plate as an added bonus. My
kids enjoyed this "hole" to below. They would pass things back and forth, or "peek" through it. It made for some added ventilation on hot days, or when
cooking. In general, it was a super low cost solution that turned out great.
They might be called access plates, or
deck ports, or something similar. They come in a variety of sizes, most likely one to fit your hole exactly.