Sounds like you’re trying to give someone a seizure…
You could probably find a way to accomplish this, but you could not necessarily find a way to guarantee the image was switched each interval unless you’re not modifying the scene and you set up to preserve the backbuffer.
Not really. You don’t have that level of access. If a card already supports 10-10-10 RGB as a native framebuffer format, then you might be able to just use that. No gurantees, though.
Paletted color is not really supported anymore. You can accomplish pretty much the same thing using 1D textures, though.