Theoretically, yes. A human would be smart enough not to drive right into a painted wall, using only their eyeballs combined with their intelligence and sense of self-preservation. A smart enough vision system should be able to do the same.
Using something like LIDAR to directly sense obstacles would a lot more practical and reliable. LIDAR certainly has enough distance (airplanes use it too), though I don't know about the systems Tesla used specifically.
That's true, but the supply vastly outstrips the demand. They may make great Linux machines, but the majority of 10-15 year old computers have little to no economic value.