Auto levelling,clamped airplane rotation

Hi all, Im tearing my hair out with this one. First off I have a drone object with a rigidbody, I move it using the rigidbody. From what I've read if you move using rigidbody then you should rotate using rigidbody. So I have this code:

  eulerAngleVelocity = Vector3.zero;
 
         if (velocity.x < 0)
             eulerAngleVelocity.z = 85;
         else if (velocity.x > 0)
             eulerAngleVelocity.z = -85;
 
          if(velocity.y > 0) {
              eulerAngleVelocity.x = -85;
         }
          else if (velocity.y < 0) {
              eulerAngleVelocity.x = 85;
         }
       Quaternion deltaRotation = Quaternion.Euler(eulerAngleVelocity * Time.fixedDeltaTime);
         rigidbody.MoveRotation(rigidbody.rotation * deltaRotation);

Which works. When I move left the drone rolls left, I move up and it rotates up. However I have two problems. 1) How can I clamp the rotation? Rolling is fine but I only want it to rotate say 30 degrees above/below the x axis. 2) When I stop pressing left(or whatever) I want the drone (on the z axis) to return to zero rotation, a sort of auto level. I've not really found any useful guides to this kind of thing and the unity documentation aint exactly clear. Any help would be much appreciated. Thanks!!