How do they send pictures back to Earth?

Since dust seems to be a potential problem for solar panels and cameras, why do landers not have a small reservoir of compressed air that might be used to blow off dust when needed?

Why don't the rovers take more color photos?

What is the visual resolution of the orbiters' cameras?

What is the optical resolution on the orbiters' cameras?

Does Curiosity have a microscope-camera? If so, when will we begin seeing pictures of that type?

Can Curiosity's cameras film in 3-D?