I'm a Trooper and I have no problem with someone being armed as long as A) their hands are visible and on the steering wheel and B) they have common sense..namely they are not rummaging under their seat or in the glove box as I'm making my approach with the intention of holding it up and saying, "Just want to let you know I have this".
Keep your hands in sight, don't act squirrelly and I won't get bent out of shape. I cant speak for other officers or Troopers but personally, I'm all about law-abiding citizens being armed and if they end up in a confrontation where a BG gets put down and they are in the clear..I will be the first one to pat them on the back and say, "Good job".
Also, yes we can obtain speeds of vehicles coming from the opposite direction. The model I have in my patrol car is a Golden Eagle II and it has that feature though I have to say the thing just collects dust. I much rather use my LIDAR set, which is much more pinpoint and accurate.
EDITED TO ADD: To the OP: Thank you for the way you handled your stop and understanding that its not personal. In my book, if you are over a certain speed you get a citation, regardless of whether you are an a-hole or very pleasant...BUT if you were pleasant, like it sounds you were..I will go out of my way to explain the procedures to go for probation, taking a drivers improvement course, etc. I also have the option of whether I want to cite you for the highest speed in the tracking history or the lowest. Depending on the speed you were going that could be the difference between a 1, 2, or 5pt citation.