I don't understand correlation coefficient well and I have few questions related to it.

1)Can I say that correlation is based on slope concept?

2)Does the correlation coefficient show how much are data points scattered on the plane?

3)Correlation varies between -1 and 1. Does this mean that the line with a slope larger than 1 or smaller than -1 (e.g. 1000, -320) will have correlation of 1 or -1?

4)What if I have a line y=5 (slope of which is zero) or x=5 (with undefined slope)?

5)If I have data points very near to each other but they don't form any specific line, does this mean that the scatter plot will have correlation coefficient of zero?