Re: rkhunter warnings, virus?
Rkhunter doesn't look for viruses, it looks for rootkits. Linux rootkits, not Windows ones.
The /dev and "hidden files and directories" warnings are something I've always had; I suggest ignoring those. The warnings about the unhide program are probably also false alarms - they are used by rkhunter. If you're worried about them, you can use Synaptic Package Manager to reinstall "unhide".
Rkhunter also has a log file that gives more information; at the end of your scan it should tell you the location of it.
If you're running an up-to-date system, and you don't have any outward-facing services accessible from the Internet (i.e. your router has a firewall that doesn't have any ports allowed), then there is no realistic way you can get a rootkit.
I try to treat the cause, not the symptom. I avoid the terminal in instructions, unless it's easier or necessary. My instructions will work within the Ubuntu system, instead of breaking or subverting it. Those are the three guarantees to the helpee.