No, you won't need to do water changes once there aren't any animals in there creating waste. Just keep in mind that the beneficial bacteria will start to starve at some point, so you may want to add some waste from time to time.
oh hmm, I would probaly have the quarantine next to the main tank or close to it so I could change the water every time I do water changes on the main tank, but I don't want it to be as much work as the main tank ahaI will be completely honest here. Unless you buy a steady stream of fish maintaining an empty qt tank is just a pain. It was just as much work as one of my display tanks. You need to still add something to feed the bacteria just as you would fish. That food makes waist and the cycles still produces nitrates so water changes are needed. If you neglect your qt your water conditions will be very different from both your tap and main tank