6. There are three modes of heat transfer: conduction, convection, and radiation. Convection is usually the fastest of these, but with no atmosphere there can be no convection. Conduction is usually a lot slower, and requires the thing being heated (the camera) to be in direct contact with the thing doing the heating (the lunar surface). Since the camera was always isolated from the lunar surface (either by a tripod or by being held by astronauts in their temperature-controlled suits), this wouldn't be a significant factor either. Radiation (in this case, heat absorbed by sunlight) is the slowest of all, which would be the primary mode of heating for any equipment on the moon. It would take several days for a camera to heat up enough via radiation to melt the film inside, and none of the lunar EVAs were long enough for this to occur.
7. It did leave a small crater, and kick up a bunch of dust. In fact, if you read the transcript of radio communications during the Apollo 11 landing, Neil Armstrong mentions there being lots of dust, greatly reducing visibility. But with no atmosphere to make particles float, the dust falls right back to the surface and settles almost immediately after the engine shuts off.
8. The dust on the lunar surface is many feet thick, and wasn't all blown away by the engines (keep in mind the engines shut off several feet before the LEM actually landed, and just dropped the rest of the way). Also, lunar dust is much different from the sand you're used to on earth that is relatively smooth due to the erosion which formed it. Lunar dust is formed entirely by rock being pulverized by meteorite impacts; it is very sharp and particles cling together without any binder like water. This makes it possible to leave well defined footprints.
9. With no atmosphere, the dust would not swirl. It would be blown straight outwards from the vehicle. It makes perfect sense that there's no dust on top of the footpads.