can I convert an iPod into an i phone?

No. There are some apps that let you send SMS messages, and you can make phone calls with an app like Skype. However, on the hardware level you can't - and that means no cell service, no GPS, etc.

No but you can try Viber.

https://itunes.apple.com/sg/app/viber-free-phone-calls-text/id382617920?mt=8

You can also install Magic Jack from the App Store. It will make calls like a phone but instead of a cell network you'll have to be nearby your Wi-Fi network instead.