According to Ashwin Vasavada, JPL's Mars Science Laboratory deputy project scientist, the slight haze seen in panorama shots from Curiosity is atmospheric dust usually present during the Martian summer.
You're right, NASA has done this with other rovers and emphasized that this software update was planned a long time ago. Curiosity will be the most autonomous rover ever landed on Mars, and that requires plenty of reprogramming.
BTW, NASA said it expects the first drive on Gale Crater to occur as early as next week.
It won't crash as Curiosity has redundant computers. Even if the update fails, it will have its recovery mechanism. But really I can't imagining upgrading a firmware from Earth to Mars! Truely amazing!
The picture is nice. What time of the day on Mars this was taken? Looks dawn to me :)