Two engineer questions
In terms of question 1) my experience has been that the further away you are from the target, the less accurate your dart volley seems to get. If I am at the extreme range of my pistol, I might hit once, but when I am right on top of my enemy, I can often hit all 5… I could be way wrong, but that has been my experience so far.
As to your number 2 question, I couldn’t tell you, I don’t use the flame thrower much lol.