Nibiru orbits the Sun about every 11 years. It has parallel bands and a great red spot. It is a gas giant and has many natural satellites.
Nibiru is an old name for the planet we call Jupiter.
As for the 3600 year planet, it was a fake invented by the fraudulent scholar Zechariah Sitchin. According to his lies, it will be near the Earth in 2085 or about the year 3000. Since he is dead, he cannot complain about other frauds dragging his nice imaginary planet into their imaginary disaster in 2012. All 2012 prophecies are lies.
EDIT - Thanks abstract.