I'm also new -- only been vaping about 3 weeks now. You can re-use the cartridges that come with your kit. I just rinse mine out with hot water. Take the little "poly-fill" stuff out first and rinse it out separately -- you don't want to lose it. There are lots of threads and even videos on the forum here to show you how to do it.
Yes, you will need extra batteries. I was a 2-pack/day smoker and I have 4 batteries, which is more than enough. Usually you'll have one on the charger while you are using another one. I have the other 2 as backups. Plus now I have a USB passthrough to use when I am working at my computer.
If you want to try some sample-size liquids at a decent price, I can recommend RockyMountainVapor.com -- $6 for 10-ml sample size. The samples are all 18mg nicotine. At first I thought it would be too much nic for me, but turns out it wasn't. I've ordered 3 times from them now. Free shipping if your total is over $14, and they are super fast, too. I can highly recommend them. Plus RMV has great prices if you want to order the larger 30-ml or 50-ml sizes.
Others here on the forum love the TotallyWicked juices as well. Either way, using the liquids and refilling your cartridges is way cheaper than buying the pre-filled cartridges. Plus it gives you a little more freedom to experiment with mixing the flavors. I love the RY4 tobacco mixed with the vanilla flavor; I'm sure you'll discover some fantastic flavors as well.
I am not implying that these 2 suppliers are the only good ones -- just the ones I have personally used. If you look in the Suppliers section of the forum, plus also the e-liquid review section, you will see that many forum members recommend other suppliers as well.
