Angular Momentum

Angular momentum is conserved as long as no net torque is applied. For an object in orbit, does gravity apply a torque?

No - because the force points toward the point around which rotation occurs there is no torque.

This means we can apply angular momentum conservation. At all points in the orbit angular momentum is conserved - for an elliptical orbit as r increases the speed must be reduced to compensate for that, and vice versa.