I've just started rereading the book after seeing the movie last week. It does briefly describe the descent vehicle and it sounds like it was a very basic capsule with parachutes and thrusters (not powerful enough to lift it-s own weight). Being a (mostly) parachute-based lander, I suspect they would have landed some way from the camp, and would have left the lander where it landed. On point 3 I was disappointed (but not surprised) they went ahead with it. I also didn't like they swapped the people around so it was Commander Lewis 'redeeming herself' by being the one that went out to rescue him. Being the commander she would have know her job was to, well, command. She had 2 other crew memebrs who were clearly the EVA specialists, so taking their place goes against the calm and professional disposition she, as the commander, would have had.