Is a fuzzy black spider with a white dot on it's back poison?

That would be a "Daring Jumping Spider", or Phidippus audax. They are harmless and not aggressive, but yes, they CAN jump, very well in fact. They hunt just like tiny cats, stalking and pouncing on insect prey, sometimes taking down insects much larger than themselves. They do seem to enjoy interacting with humans, for some reason, possibly because they are actually very intelligent creatures, and because their eye configuration is a bit like ours, with two large forward-facing eyes.