No, because we don't colonise the solar system using the surfaces of planets and moons — we do it by mining asteroids and building giant rotating habitats. There is enough material in just the asteroids alone to build habitats with a land area of millions of times the earth.
Look up the work of Gerard K. O'Neill or John S. Lewis for details.
Yes to this. Most of the spherical bodies in the solar system are so inhospitable that making a spinning cylinder full of air is actually much easier and more useful.
Depends on if you include the oceans. Mars is not that big, but lack of oceans more than makes up for it. On top of that we mostly ignore huge chunks of the land mass like Antarctica.
Sad!