I've been a robotics hobbyist for a few years and still can't answer any of those questions. I can get my turtlebot to follow me around and chase the cat though. Is there a practical programming robotics book/course out there? I've taken tons of math, controls, read robotics books, but still can't program anything harder than a PID or Kalman filter. I think part of that is me relying on ROS libraries too much.