It means it has a virus, usually from jailbreaking and stealing 'hacked' applications.
A tracking cookie is not a virus. Sometimes the cookies can be from harmful sites, but the cookie itself does have a virus.
A PC virus reaches your computer/PC from the world wide web. A virus can be accumulated from various sites such as : xxx sites(Pornography), proxy, and even email.
Downloading files that are attached with a virus. Only download from trustworthy sites
obviously, as you cannot get them w/o jailbreaking
Yes, like any laptop or computer, but Apple has lots of safety measures to protect it. Jailbreaking would void those measures.
bitlord
Yes, jailbreaking does void the warranty.
"Jailbreaking" is another word hacking. Therefore you void your warranty but you get cydia, a jailbreaking software. Jailbreaking does have it advantages and Disadvantages. But if you want to send it to apple to repair it you have to restore it to factory settings to get back your warranty.
Yes; not jailbreaking it. If you mean a way to do the same thing as jailbreaking without actually doing so, there is no current way to do so.
Jailbreaking a phone is partially legal and partially illegal. I have a post regarding this http://www.techlucid.com/2013/11/is-jailbreaking-illegal-or-not/
yes certain anti-virus software does abort connections with harmful sites but some anti-virus software does not so it leaves you open to worms and trojans.