What does it mean when the vp shunt reservoir is hard/soft/flat/round? the speed it refills? how can one know if they're still dependent on it?

Nothing specific: Different shunt valves have different configurations. In general, the valve reservoir should depress and refill. I would not encourage frequent "pumping" of the reservoir though as this can draw debris into the shunt and clog it and provides no real clinical information as to whether the shunt is working or whether a patient still needs a shunt. Shunt dependency requires a md evaluation.

May reflect function: The vp shunt reservoir can have different shapes depending on the type. The most common/ most useful is the round reservoir. This is connected to the tube that goes into the ventricular fluid in the brain. If it pumps and fills readily, this suggests that it is in continuity and thus working. If it pumps but fills slowly, this suggests some occlusion at the tip.If it doesn't pump, likely occluded.