Flasponge... I'm sorry, but I simply do not agree! I have been vaping almost 2 months now and e-cigs have been a miracle for me and, I assume, the vast majority of people here. I don't run out of breath when hiking nearly as easily, find it much easier to get through my daily yoga routines, have much more energy, and cough rarely, if ever (and when I do, I realize it's because my lungs are recovering from years of inhaling carcinogens). I have heard that the few detrimental effects of nicotine are comparable to that of caffeine. I would assume that these side-effects you are experiencing could be attributed to smoking analogs and are just now surfacing as your body tries to recover. Keep in mind that it takes 7 years on average for the human body to recover from cigarette use.
That being said...
freeall, I am also new to this forum but like I said, I've been vaping for about 2 months. Congratulations on taking this huge step! My initial kit was a Cig2o (KR808D-1, as I've been informed) starter kit that came with 18mg nic cartos. I went through them quickly, so I switched to 24mg's to get me through the first few weeks (I was smoking American Spirits for about 5 years prior to quitting). Obviously the amount you were smoking coupled with brand will factor into the level of nic you will need initially to make the switch. I agree that you will probably need at LEAST 12mg initially. At this time I have been able to taper down to 8mg and 11mg nic carts/e-liquid depending on the supplier.