Orbiting And Speed
First make the max speed limit realistically just under the speed of light and after a you reach .10C (C is light) display the speed in .C not m/s. Then add an escape velocity for all the planets. At this point you can make an orbit as well. A orbit UI in the ship would be useful for showing the required speed the speed you need to reach your direction and how your orbit looks around the planet. Also add presets for orbit and an auto pilot for it. As for getting between planets when you use the jump drive your ship should keep its velocity and direction. For getting to other planets just using thrusters I can't think of anything for that.