Here is a good guide to vaping that will answer most of your questions:
Here is another shorter version that discusses some of the terminology and answers basic questions:
Starting vaping (we call it vaping instead of smoking because what you inhale is mostly water vapor with a touch of nicotine) can have a bit of a
learning curve because you have to find the right device and nicotine liquid (strength and flavor) that work for you.
As of April 2010, The American Association of Public Health Physicians
(AAPHP) supports electronic cigarettes sales to adults, "because the
possibility exists to save the lives of four million of the eight
million current adult American smokers who will otherwise die of a
tobacco-related illness over the next twenty years." However, the
AAPHP is against sales to minors. The AAPHP recommends that the
FDA reclassify the electronic cigarette as a tobacco product (as
opposed to a drug/device combination).
First we begin with lots of good information and reviews of ecig devices and nicotine juices