Some basalts may be older than some sandstones, but ages of sandstones and basalts vary tremendously. Some sandstones are therefore older than some basalts. Oceanic basalts are rarely over 200...
because the sandstone is smooth and big
sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains
Probably because it is worn down rocks, and those are colors they tend to be
Water fills the pore spaces between the sand particles, making is heavier.