Answer: 180 degrees
The angles of a triangle always sum to 180 degrees.

Answer: 4 trivial factors.
The positive +1 and +N and the negative -1 and -N.

Answer: 73

Answer: Yes, it is!
Adding up the divisors of 8128: 1 + 2 + 4 + 8 + 16 + 32 + 64 + 127 + 254 + 508 + 1016 + 2032 + 4064 = 8128

Answer: Paul Erdős, of course!
As the Erdős number describes the "collaborative distance" in authorship of mathematical papers between mathematician Paul Erdős and another person it is only natural that Paul Erdős holds this position.

Answer: 5
Portman collaborated (using her birth name, Natalie Hershlag) with Abigail A. Baird, who has a collaboration path (Gazzaniga, Michael S. -> Victor, Jonathan D.) leading to Joseph Gillis, who has an Erdős number of 1.

Answer: 49

Answer: 333

Answer: 3
Russell collaborated very little and no Erdös number can be found using research articles. But, as pointed out by Sachi Sri Kantha at "the Erdös number project" Russell and Albert Einstein did coauthor the Russell-Einstein "Peace" Manifesto of 1955.

Answer: 91