Yes that should work. Just keep in mind that there is only one set of preamps being used (in this case – in the GX4816), so each desk will share the preamp gain setting. If one person changes the gain setting, it effects the gain setting at both monitors and FOH. The good news is that the SQ series has an additional trim setting that allows for independent gain control. Just keep in mind that the trim functionality doesn’t span the entire range like the preamp gain setting does. The preamp gain control is 0db to +60db while the trim control is +/- 24db from the set preamp gain setting.
As far as setting up the Dante network, it is always easiest to have a Dante only network – meaning only Dante devices are connected. If you can accomplish this, then just about any network switch will work as long as it doesn’t have any “green” power savings features turned on.
If you are trying to put Dante and non-Dante devices on the same network, then it becomes much harder to get a stable Dante network set up. It is certainly doable, but requires a much higher level of network knowledge to troubleshoot the issues that are likely to arise. If you can keep it to a “Dante only” network, the system is basically plug and play.