1. Humans and their evolutionary descendants have spread throughout the solar system, possibly beyond that.
2. Mars (Stelt) has been terraformed to an extent, though some factors like gravity haven't changed.
3. Yes.
4. I didn't give too much thought to elemental powers and other "magical" elements. Since the direction is indeed a harder sci-fi, any "magic" would either be replaced with technology or done away with entirely. E.g. Kanohi mask powers such as respiration or night vision would be attained through technological means.