Your coils don't have to be straight, but it is really easy to tweak them with whatever tool you wound on, it is also best for flavor to have a more direct airflow, I usually prefer my coils slightly above the Air holes, by slightly that is the bottom half of the coil is fairly in front of the hole. You can play with height to find your preference. But direct aiflow usually provides best flavor.
Amount of cotton is also a preference more then a set rule, make sure your coils clear the cap. One advantage to a level coil is you can more easily keep the tails even for feeding. the Atomic is pretty decent for heavy cotton since it basically has no juice well.
I pulled out my Atomic to take a couple picks of the current build in it, unfortunately my batts are dead in my camera.