The standard M battery that comes with the kit is an automatic battery. An auto battery automatically works when you inhale on it. A manual battery only works if you hold the button on the battery. Although I thought auto would be easier, for me manual is better because I can take longer vape hits off it. If you are ordering the kit remember it only comes with one automizer, so you might want to get another as your volcano one won’t fit the magna.
Liquid is used if you want to fill your own carts instead of buying pre-filled ones. You can buy blank carts (which are out of stock right now), or refill the pre-filled once they are empty. I perfer to fill my own because it is cheaper. There are alot of places that sell juices and you can find 100′s of flavors or make your own.
Volcano has its own forum which can give you lots of info on their specific products. The people on that forum usually answer all questions!