What is the mass of Nibiru?
You'll hear anything from 4 times to mass of Earth to 4 or 5 times the mass of Jupiter usually. Nobody can agree of course, throws a bit of a spanner in the works…
How close does it get to Earth?
Again, the consensus is of 'no impact, just a fly by', but that it will go between either the Earth and the Sun, or Mars and Jupiter. But seeing as between Mars and Jupiter is nothing interesting (and by interesting proponents generally mean 'Earth'), it's usually the former.
What is it’s orbital period. 3600 every turn? And why?
Dates back to Zechariah Sitchin, though I think some others have done some numerology nonsense around it. It seems to be the number everyone agrees on, though you'll get disagreements over when it gets close, rather than how long. Again 2012, as this site suggests, is the first number to come about, and not the dates offered by Sitchin himself, who was closer to 2112 than 2012.
Funny how proponents just don't care about the details. But it's good to see yet more YouTube firepower against these claims, keep it up.