Welcome to ECF and vaping. Know that this is the best and easiest way for your wife to give up tobacco when she is ready. It may take some time. Some people start vaping and they can put the cigarettes down pretty quick. Other people take a lot longer. The fact that you will be vaping with her is wonderful. It is a show of support and I bet becomes an enjoyable hobby for you too.
The setup you have is a good starter. You will need backup batteries for when one is charging. I suggest an Ego Twist 1300mah or a Spinner 1300mah. These have batteries that will last for the whole day and have variable voltage; a feature where you can adjust the power you get so that you can turn it up or down to get the best taste out of the juice.
The Evod is a good, reliable topper and will serve you well. You can buy replacement heads for it. Get the real Kanger ones, they are a better quality and you will have less trouble with them. Do not throw out the little heads. Rinse them and save them. Down the road you may want to rebuild them and save yourself a lot of money and the juices will taste better when you rebuild them.
I know. Lots of information in the beginning. You will catch on real quick. Just know that you can come on here any time and ask any questions you want. Someone is always here to help. Here is a link to a post that will hook you up with a lot of info you can read to get a good start.
http://www.e-cigarette-forum.com/fo...op-reference-shop-new-experienced-vapers.html
Finding flavors you both like will be a trial and error thing. Since she probably smokes more than you, you may need to get different levels of nicotine in your juices. If she is having trouble with the vaping not be satisfying, she may need a higher nicotine level. You should not vape a high nicotine level if you are not a constant smoker. If you have a local vape shop that makes their own juices, see if you can work with them to maybe give you some 0 nic juice at a discount since you will be buying some stuff double for nic levels.