2 just solve dy/dx according to dy/dx = sec (x+y) 2 * (1+dy/dx).

3 The tangent slope is the intersection of 1/e (e, 1).

/4 Divide the integral into two terms. The former term is 0, because the integrand function is odd function.

I'm sorry, I didn't work out the result, but I just provided ideas, hoping to help you! !