16mg is a strange nic level. Of course you are also in Canada, they may have different standard levels than we do in the States. I've heard of people quitting at 18mg, so I know its not impossible (of course there are those who did it on 6mg too). If the 16 isn't cutting it on nic then you need to up the level. If you're feeling dizzy or nausious that might be an indication that the nic level is too high and you would need to lower it. Trying to translate from cigarette habit to e-juice is difficult and add to that the symptoms for nicotine over dose and nicotine withdrawal are similar makes figuring it out worse. And then get some juices you think you may like.
I will warn you though, if you don't like them at first, keep them anyway. Some juices age like fine wine, others age like fish. Its called steeping. The ones you don't like are a nice back up--and you can maybe vape them if you have a cold or have vaper's tongue (a condition where you lose your sense of taste for a while--it has many causes and just as many treatments). Since you can't taste anything under such conditions anyway--you won't care what they taste like.
As to the coughing. That can be from several causes. First the smoking, it makes you cough--smoker's cough we all know about it. But also trying to inhale your pv like a cigarette can cause it to.
http://www.e-cigarette-forum.com/forum/ecf-library/337017-inhalation-technique-e-cigarette.html
I coughed a bit at first too until I learned how to inhale that worked for me. Since I was a pipe smoker it was a bit easier for me as taking a drag from the lungs with a pipe is not really something you want to do--even the crappiest pipe tobacco is stronger than most cigarette tobacco (well at least in the States). So I gently draw the vapor into my mouth by creating suction with my cheeks. Its kinda hard to describe exactly, its something one has to well teach themselves to do.
Then I hold the vapor in my mouth for a bit, usually around 4 or 5 seconds. Since the properties of vapor are different than smoke nicotine absorption through the mucus membranes of the mouth, throat and nose absorb the nicotine better than the lungs do. I then do a shallow inhale into my lungs (basically enough to have air to exhale) and then exhale through the nose.
As to buying juices, since your tastes can and will change on short notice and sometimes without warning, I would suggest getting smaller bottles at first until you find something you like a lot. I wouldn't buy over 15ml unless I know I like it--and sample bottles (between 3-5 ml) are great for trying flavors.
