Basically I have a router which allows wired and wifi connections. I'm using Tails on my desktop computer through a wired connection. We have cell phones that then accesses the wifi on the same network to browse the regular net, download updates etc while I'm using Tails on my desktop (no tor or Tails on the cell phones). Any way authorities can see what I'm doing on the desktop or grab my real IP address etc while Tails is running on the desktop and the cell phones are browsing the regular net and downloading etc? Note that this is NOT a public wifi connection.
The fact that Tails and your phones / other devices use the same network does not make a difference.
Your ISP or any adversary that monitors you, will know that you use Tor, but can not decrypt your traffic. An adversary that monitors the site you visit will know that someone is using Tor, and if the service is unencrypted, can see the traffic.
Well, it shouldn't be a problem. If you have 2 pc's on one wifi network they will have the same EXTERNAL ip address. Now you are using Tails which means that ip on one of your devices will be masked. You could unmask it by logging in a website that you previously logged in with your phone using your real ip. If the ISP and the website is tracking you and you connect with both your pc and phone at the same time on the same website they could POSSIBLY find out your real ip. Or at least it would be easier for them if Tor doesn't change the circuit each 10 minutes.