I joined back in November right after recieving my first iPhone. This has to be one of the most informative forums I've been on. You'll get your answers, just make sure you search first as to not duplicate. 9 times out of 10 you'll find the answer to your question.
No, do not worry about any iPhone viruses or malware. Don't even think about it as long as you use the Apple Store for your app downloads. The Android devices are more susceptible to malware because their "store" is not as clean as Apple's is. Don't give it a second thought for now. In the meanwhile, I'm sure there are hackers out there who are working to mess with the iPhone. But so far, no luck for them!!