Question 1. Does iPhone 5 have antivirus software installed? 2. What (free) software does 2.iPhone 5 use to block harassing calls and text messages?

Well, you don't need to install anti-virus software without jailbreaking, because all the software you installed has been verified in the Apple appstore. There is only one way to block harassing phone calls and text messages without jailbreaking, that is, do not disturb mode (he only has white list function), which can be set by selecting Setup-Do not disturb mode or Setup-Notification-Do not disturb mode, with different functions. If you don't understand what I said, just go to Weifeng forum and search it. There are many detailed explanations on it. If you break out of prison, there will be many softwares with these functions.