How much does the facetime cost on iPhone 5?

Is it free? I heard that its free if there's Wi-Fi, is it true? Should the "use cellular data" be on if i want it for free? I faced time with my friend for like 1 and half hour, and the "cellular data" was one, did it cost any?

It's up to your service provider. You know like the AT&T and Verizon. Facetime uses internet so to call someone when you have Wi-Fi, it's free, because Wi-Fi is free. But when using cellular data, it depends on your service provider because if you have free cellular data, then it'll be free and if you don't, you'll have to pay.

Yes it is free via Wi-Fi. If not then it will be charged for since you would be on a data plan at that point.