Only once overseas, when on a learning trip in China, i used my ipad (not mini) to facetime with my parents every night, thanks to the hotel's free wifi.
Otherwise, never. If I need to see my friends, I would simply invite them out for a meal or drink. I do know of a friend whose family is in another country, and he uses his ipad to facetime with his wife and kid every night.
I have only used FaceTime once on my phone. My fiancee and I tested it when we first got our iPhone4s. I haven't used it on my iPad but I have been using Skype to make video calls to non-Apple using family members lately.
Only with certain family, to be honest. Maybe once or twice a month. Never once used it with friends. I think it's just a little too invasive to be used frequently. There's something comforting about being able to chat without the other person actually seeing your every move.
I Facetime regularly with my Grandmother She has an iPad 2 en she is 78 years old. I have a mini. Facetime is so much easier to use than the skype app.
Never. I like to multi-task, so when I'm chatting on the phone, I want to be able to move around and do other things such as cook, fold laundry, etc. My cordless phone lets me do that.