1)

If you square each correlation coefficient, you'll get r^2 - the coefficient of determination, which is the percentage of the variation in y due to the variation in x.

2)

the equation of any linear best fit line is the form y = mx + b where m is the slope and b is the y-intercept (value of y when x=0)

the following link shows you the equations for finding m and b from data - go down approx 1/3 of the page:

Regression: Fitting Functions to Data