1. Why are there 360 degrees in a one revolution?

The Zodiac was first divided into 360. The Greek astronomer Hipparchus first divided a circle into 360 degrees. 360 is also approximately the number of days in a year.

2.Are vertically opposite angles always equal?

Yes.

3. Are congruent angles and equal angles the same thing?

Yes.
A pair of congruent angles are the same size and a pair of equal angles are the same size.