Is it likely to get a virus from other rooted devices on my LAN, if im using an ethernet cable and the other devices are on wifi?

With a Wired connection the chances are considerably lower from what I have heard other members here say. Wireless maybe but if your already running Linux your reasonably safe.

One thing you might want to do is go into your Modem or Router and change the factory set Administrative password as it can easily be found online.

If your ISP ever needs to get into the modem or router you'll need to give them the password and than you'll have to change it again if you don't want them to know.

Do some research on Can A Router Be Infected With a Virus?
Google is your friend:-

edit: just reread the question. I missed the word "rooted" here. I actually have no clue, feel free to ignore this post.

I'd recommend running nmap (you have to install it):

And closing ports you don't use. For example if you see cups listening, and you don't use a printer, then uninstall cups (or disable it, probably with systemctl disable cupsd, if i remember correctly). You can also check your router settings to make sure no ports are being forwarded and the firewall is on, and make sure it's a reasonably secure operating system with
And if you're still paranoid, look into managing iptables and checking your logs (probably with journalctl).

thanks for the feedback yeah i done some previous searching on if a router can get a virus and got mixed reasults. Some people say routers dont have an OS so it cant get infected, some say they do have a microkernal so they possibly can be infected. Ima look more into pfSense for a custom hardened firmware and wireshark and other tools etc for analysis. But thats above my know how for now im still learning how to properly use man and command line effectivly (multilple arguemnts at once etc..) I have another question though, like say i do get infected with some nasty malware. Could i just replace the hardrive and and install a fresh OS, would that get rid of it 100?

Yes, replacing the HDD and performing a fresh install would be successful.
-::<Unless the router was hacked and the encryption passphrase that your ISP gave you was also hacked.>::-

If your current HDD is infected with a virus you could do what's called a zero fill or use software to completely wipe the disk.

http://www.dban.org/
http://helpdeskgeek.com/free-tools-r...-a-hard-drive/

Man pages are often hard to understand. Start here first:-

http://linuxcommand.org/learning_the_shell.php
http://ryanstutorials.net/linuxtutorial/

Good to know, good to know thanks you all been a big help ill check out those links in a bit too, im like a hoarder of infromation lol i have a bunch of vids/things to read xD Thanks bros!!

Your Welcome:-