Yes and No. If you have an active data package then you could use that or your personal wifi.
You can use Spotify, IHeartRadio, Pandora, and such over a 3G or LTE network, but it'll eat up your data.
iHeartradio is 100% Free. Its ad supported however.
Some of the stations are live. You can set up a custom station as well on iHeartradio.
Yes you do need wifi
Yes, you need wifi to FaceTime.
You need Wifi to do anything on YouTube.
Yes you need WiFi
You only need WiFi if you are downloading new books. Books already downloaded do not need wifi
WiFi usb adapter is a WiFi card.
No wifi
No.
You need a wifi router or a Nintendo wifi usb