It does have PIP. I believe it is 2 signals at once. The channel you are watching and another external source such as from a bluray/cable/sat box. Hope this helps. I still love this unit after even owning it awhile.
I have the 65" and i guess they both function as the same. Yes, it does have picture in picture and it is right on the remote button on the infrared remote. It came with 2 different kinds of remotes.
I have not actually play the PIP channels to see if both channels can play the same time in parallel if that is your question.
However, I can tell you that when I am surfing the web on the TV, it minimizes the picture and moves it to the corner while playing it. You need a keyboard from Samsung, I got one. I will try to see if it can play the PIP in parallel, I doubt the audio will play in parallel, think about that.
The set does have some ability to do PIP. You should go to Samsung's web site and see all the advertised features, including input sources, that this model offers. However, one thing to keep in mind -- The set comes with two different types of remotes, including one you can speak commands into but if you hook your TV up to either cable or sattelite like probably 99% would then those remotes are mostly useless. You'd use the remote that ATT Uverse, or Comcast, or Cox, or Time Warner, or DirectTV, or Dish, or Verizon, or whoever offers with their box.
I don't know the answer to your question but if you're a videophile or like a fabulous picture stay way from Samsung. Their picture suffers due to the ultra-thin profile of their TV. Best to go with Sony or Panasonic for LED, or even the new Vizio 60" got decent reviews from Home Theatre Magazine .