I honestly don't understand how people can run the Nautilus with such a low power. I had been running mine between 12-13 watts for my ADV, with very occasional gurgling that was always easy to fix. What I could not tolerate was juice being splattered into my mouth. I have been running the Mini on my iStick at 15 watts and there has been zero gurgles, juice splatter, or flooding. The 1.8 ohm coils are rated up to 6.0 volts, which equates to roughly 20 watts, so there's no need to limit things to as little as 7 watts.
Some people like a cooler vape and are satisfied with what they get at 7-9 watts. Just remember that the airflow needs to be open all the way. Too tight an airflow will cause it to draw too much juice onto the coils, faster than the coils are boiling it off. If it sits and starts leaking like you've described, I'm willing to bet you have a leak somewhere around one of your seals that is letting air into the tank.