hmm...i'm not sure i know how to answer all of those questions.
i tend to leave mine plugged in while i vape and then let it run down. i'm not sure how good the battery life is, for this reason.
i know that you can get an accessory that allows you to charge it in a car cigarette lighter, which is pretty cool. i think if you charged it up before going out and then turned it off, you'd likely get at least a couple of hits out of it (maybe more) but i can't really verify that because i've only ever used mine in my home or wherever i'm staying. it's nice to be able to get high in a no-smoking hotel room
after packing a hit, i tend to hit it for 10+ minutes.
something cool i've noticed is that the more i use the vaporiser, the more "vape resin" seems to build up inside it.
it's not like skanky bong resin, it's like a sweet liquid form of the vapours that have solidified in the mouth tube or something. liquid hash oil.
these seem to heat up over time, and i tend to get heaps of really nice hits long after i would assume the weed inside would be spent.
these vapours - i don't know what to call them, but they're like post-herb residual vapours - are not in any way inferior to the vapour from the weed, it's like smoking nice hash.
so it kinda makes an informed judgement about how many hits you get from one packing kinda hard to make.
i can tell you it is fucking brilliant - but i'm afraid i can't give you a really good answer. i'm sure someone on Bluelight could though, in Cannabis Discussion subforum. i understand the importance of making the right purchase decision because they are so expensive and so many to choose from on the market that you need to get the right one for your needs.
oh, but i generally set the temp at ~375 degrees Fahrenheit and then move it up to 400 degrees (the max. temp) for a second lot of vape. i've read that different cannabinoids vapourise at different temperatures, and the pot certainly seem to get a new lease on life when you turn up the temperature for a second go at it.
i'm not particularly well-versed in these matters, and just use it as i've been shown by friends. i should do some more research to learn how to get the most out of it.
the mouth tube gets a bit moist with this oil, and i know a guy who sticks a cigarette in there to clean it out, then smokes the cigarette and gets really high.
on top of the fact that i use a keif grinder (collecting hash for later) and i get a heap of bonus smoke from the vaporiser, i feel like i'm getting the absolute best from my weed. when i found out i can cook with the vaped buds, i realised that i'm pretty much getting 3 or 4 different highs from the same bud. certainly helps justify the expense of a vapouriser for me.
i have a pretty high weed tolerance - especially for edible cannabis - and the 2-3 grams of vaped buds i cooked were almost too much, and i lost a whole day.
i'm never going back to combusting my cannabis.