My Squeezeboz Touch is connected to my Synology NAS wirelessly. How much of a difference soundvise is there between wired and wireless. I would rather not have my NAS close to my stereo setup because of the fan noise.
No difference sound wise. Of course, wireless connection is prone to dropouts. But as you said, fan noise is an issue when it's close to your stereo setup.
None. But having a 'double' wi-fi link of streamer-<>-router-<>-NAS is one of the main causes of unreliable working, you're generally best to wire the NAS to the router and wi-fi the streamer.