Hi Mike,
V2 e-cigs are a rechargeable battery type. What sets them apart is that they have 808 threads on top; meaning the liquid delivery top has to be compatible with the battery. There are 2 different type batteries-manual, which means you have to depress a button on the battery that provides the vapor from the cartridge and auto, which means as soon as you draw from the cartridge the battery produces vapor.
I also use the battery passthrough which eliminates recharging the battery. On the V2 website, look for the tab that says connect with us and choose forum from the drop-down menu. You will find a lot of helpful information there.
I literally quit smoking cigarettes within 3 days of using V2 e-cigs! I've added some different hardware to my vaping, but my v2 is always nearby because it's quite convenient to use.
I've refilled prefilled cartridges, with good results. I've used the EX blanks-they work great with the passthrough to test e liquid flavors. I would recommend buying cartridges when they are on sale-the expense can add up.
In my opinion, v2 is a wonderful beginning point for anyone switching to vaping. It's pretty much a no-brainer system and quite easy to use. The longer batteries allow more time between charges, but the shorter batteries fit nicely in your hand when you don't want to be obvious about your vaping. I have no regrets buying the v2 and continue to use it daily because it is so convenient to have around.
Happy vaping!