Compare dates, highlight cell

Can anyone help me determine the proper formula(s) to express the following required functions?

If Cell Date in Column B is the same as Cell Date in Column A, Cell in Column C is 0
B1(4/20/16) A1(4/20/16) C1(0)
If Cell Date in Column B is 1 day > Cell Date Column A, Cell in Column C is 1
B1(4/21/16) A1(4/20/16) C1(1)
If Cell Date in Column B is 2 day > Cell Date Column A, Cell in Column C is 2
B1(4/22/16) A1(4/20/16) C1(2)
If Cell Date in Column B is 3+days > Cell Date Column A, Cell in Column C is 3+
B1(4/25/16) A1(4/20/16) C1(3+)

THEN...

If the Cell in Column C is 0, Cell Date in Column B stays CLEAR
If the Cell in Column C is 1, Cell Date in Column B turns GREEN
If the Cell in Column C is 2, Cell Date in Column B turns YELLOW
If the Cell in Column C is 3+, Cell Date in Column B turns RED


Please see the below example that I have been doing manually.

Thank you!!!

Thank you, gak67!!!