Questions -
- what ohms is the CE2 in your tank
- what voltage are you vaping at
- what is the mix ratio and type of flavor of your juice
I had a 2.4 ohm CE2 on a 3.7V GLV with a 50/50 mix juice, the first evening I used it everything was great, but the second evening I started getting some slightly burnt taste. I took a look and the coil was already looking pretty cruddy.
I cleaned it, did a dry burn, put in a 70/30 mix ( slightly darker though ) and used it on my Ego ( 3.4V ? ) Used most of 2 days before getting an occasional burnt taste. My thought is, unless you have really light and clear juices, stay away from 2.4 ohm CE2's. I'm going to try to get some 3.2's for my GLV and see how that goes.
As far as the vapor in the tank goes; I keep my house fairly cool, so it stands to reason my tank is cool. Some of the warm vapor is naturally going to get pulled into the tank where the air is cooler. ( straight thermodynamics ) I can't see as how it would cause any problems though.
On your leaking problem, if the tank was sitting upright in the cup holder, I don't know what the problem is but there is a problem. Maybe the carto was not seated firmly in the bottom plug and you loosened it enough to leak when you took it off your PV. If the tank was laying on its side then you have to realize there are 2 holes where the wick comes into the ceramic cup. If you fluff up the wick around the coil as it leaves the cup then you minimize those holes, but you don't want to push the silicone ring down too tight onto the cup because you risk restricting the flow of juice.
On a side note - I have only had to fill my tank twice so far, but I just left the top grommet off and poured juice right into tank. No needles and no drip dripping.

The only thing I did was make sure ceramic cup was centered, then push grommet straight down into tank being careful to put even pressure around the circumference. Easy peassy
Party on dudes... I mean VAPE on dudes