Yes, definitely. There are free IPTV boxes out there that you need not pay a dime for. For example, Kodi, which is a media player is continuously being developed by the open-source community is an application anyone can use.
Yes, of course. Who gives IPTV for free over the internet or the world at large? Impossible for one for free. You will have you subscribe. Therefore it is never a free service
Yes, it is 100% legal. However, streaming it, is another question and where you reside will determine if you can stream IPTV or not. It is that straight forward and simple.
IPTV stands for Internet Protocol Television. With IPTV you can stream the source nonstop.