As on Earth, some areas have exposed rocks, but in other areas they are covered by smooth deposits, such as layers of dust drifted in by the wind. At these high speeds, the meteorite explodes and is destroyed, due to the extreme mechanical shock generated when it hits the ground. At most, you find only scattered small fragments. In general, each meteorite hit excavates about 500 times as much local soil as the mass of the meteorite itself. So, in addition to being mostly destroyed, the meteorite material is diluted by the native planetary material.
Some people think so, yes.
Still more moisture combined with minerals to oxidize them or form water of hydration, which means H2O molecules in the minerals. Because the current atmosphere on Mars is so thin. Venus is the other extreme. Venus is hotter than Mercury, even though it is not as close to the sun. Igneous rocks, such as lava flows, crystallize directly from molten material and thus are less likely to have fossils from ancient seas, though microbes could colonize them after they form.