7/16 or 11mm…

If you arrange your network with one router the other devices cabled back to the router & set to WAP mode, it’ll work as one network. Not perfectly but it does work like this. Preferably you’d want the devices set to the same settings eg all WiFi6 capable, min WPA2, AES, 20MHz for 2.4G, band steering on, etc

No, don’t use a hub.

If their device only gives you one port, you’ll likely need a router to separate your network (LAN) from the public internet (WAN). The router will look after your IP addresses & typically give you at least 4 LAN ports.

If you still need more wired connections you’d add a switch.