To be honest leaking shouldn't be an issue with the C I know it is but I don't know why.
As for flooding the atty its hard to do since the atty has a resivoir under the coil which collects juice and then you vape
That. The coil I find goes dry due to a tightly wound wick so I usually intentionally flood the atty slightly to give good flavour, just a few quick draws on the tank without pressing the power button
As for the atty where the resivoir is under the coil the plastic is raised so any excess liquid in the resivoir doesn't flow out the bottom of the atty
Here's a pic I grabbed to show you
Hope this helps