The nicotine content that you need depends on what you smoked and on how often you vape just as much as how much you smoked.
Half a pack a day of lights wont be the same as half a pack a day of full flavor 100s.
Plus, with cigs, it is easy to know how much your getting. You know you can smoke x cigs per x hours before feeling like you had a nicotine overdose. But with vaping, there is no way of accurately monitoring this as it largely depends on how often you vape, how much you inhale and how much vapor is produced when you vape (which varies based on the wattage and the atomizer used or the rebuildable coil). I went from half a pack of newports a day to using 6mg nicotine liquid with BDCs @ 4 watts and it wasn't enough nicotine. But it almost feels like I'm getting too much nicotine at times with BVCs @ 10 watts simply due to the increased vapor production.
Juice *under* the atomizer generally means flooding. This can be caused by several things, including how hard your sucking on the tip. If your not getting enough air flow, you could try turning your nautilus to a higher airflow setting if it isn't already at the largest hole (scrolling up, I see you already are though, I was thinking of taking a metal drill and making the hole bigger on my tanks). But, it can also be the result of temperature changes. At work, I vape outside on my breaks and lunch. It's cold outside, after being out there for half an hour then bringing it inside to put in my locker, it warms up, the air inside expands, and some juice gets pushed out and minor gurgling will happen when I vape later.
I've never had juice get in the threads of my nautilus atomizers, but I would have to guess thats a result of the coils not being tight enough. While the coils are supposed to be 'finger tight' this is a hugely inaccurate amount of tightness as everybody will have different levels of hand strength. Just like when one person can open a jar that somebody else can't, a tight coil for one person might not be tight for somebody else.
As for juice being in the little grove between the atomizer and the base when unscrewing it, that is somewhat normal, it's where the juice goes to flow into the atomizer head (if I'm understanding what your talking about). It's a tiny area and surface tension will help keep it in there. I leave my tanks sitting upside down when not in use (to avoid temp change flooding mentioned above) and for a few hours before unscrewing them so the fluid has plenty of time to drain from the base. Really helps out a lot. I normally vape until the tanks are nearly dry (almost none visible in the grove at the bottom), but if I want to open one that isn't empty without letting it sit for a while, I hold the tank at a 45 degree angle when unscrewing the base and unscrew it slowly so the fluid can run down from the grove. Unscrew it half way, then screw it back in again, then unscrew it all the way. Seems to prevent any issues of juice getting lost.
More PG = thinner juice. I can't really comment specifically on that though since I've always used high VG juice in my tanks, normally 80% or higher and rarely have dry hit issues after priming.
The nautilus tanks can be finicky at times. But they can also be excellent tanks once you get used to them. Just like getting used to how a new car handles so you can make it perform great. I have 3 nautilus tanks that I rotate daily and vape around 3-5ml of 6mg juice daily. After over 2 months of use I've only had 2 BDCs and 1 BVC coil go bad and I think the BVC and 1 BDC were my fault.
