I wouldn't go anywhere near 50 watts on an Aspire Nautilus... it's been a while since I used one but as far as I remember the highest I could go was about 12/13 watts without choking on burning wick. I'm assuming the 'Kangertek sub mini box combo' includes a subtank? I've never used one but I gather it could handle up to 50 watts (maybe someone else can chime in there?).
As far as the heat of vapour at higher watts - basically, the hotter your coils go, the hotter the vapour is going to be. Wider airflow will cool the vapour down a lot. This will result in more vapour and less flavour. Less airflow will give you less vapour, but it will be hotter with more intense flavour.
Essentially its all about adjusting to your liking. When I first started vaping I found I could find the sweet spot for me on most of my new gear very quickly - this is still the case, in fact.
Perhaps investing in a couple of RDA's may be a good idea if you are looking for both more flavour and more vapour... these offer the best of both worlds really but require a bit of a learning curve - there are plenty of videos on youtube that walk you through setting these up and using them that I found very helpful! If you choose to go this route I'd suggest getting a magma (good flavour atty) and a Mutation X (lots of airflow). These will give you a good experience of each extreme!
In terms of mouth to lunging - I was a mouth to lunger up untill I got my first RDA. I found (and still do) that higher watts like this made me cough and I also felt I couldn't get a comfortable draw with the bigger airflow. I now only do lung hits and find it very comfortable and more satisfying than mouth to lung.
I hope all of that made sense. Good luck!
