The point (a,b) on the curve y^2=4x+5 is above the X-axis

The point (a,b) on the curve y^2=4x+5 is above the X-axis such that the gradient at (a,b) is 2/3. Find: a. the values of a and b, b. the equation of the tangent to the curve at (a,b), c. the point at which this tangent cuts the Y-axis, d. the equation of the normal line to the curve at (a,b).