Let us begin with the basics. If an exterior perturber generates the potential W, then an originally spherical planet gets distorted. Owing to this distortion, its potential acquires an increment U which is usually called the additional tidal potential or, simply, the tidal potential.
Now let us fix a point on the surface of the planet. Let $\gamma$ be the ...
Answering your first question:
If I understand it correctly then the black hole is created by
collapse of a super massive star at the end of its life. This star
will have a finite mass. Then what leads to the black hole to have
such massive gravity so that nothing can escape it (because if it was
a star before with a finite mass then it would also ...