@GRLSNGR If you are enjoying the higher wattage range, I'd go with the .4ohm coils to start. You can always experiment with the others too. Just remember, as the resistance goes up, (.4 ohm, .6ohm, 1.0ohm) the wattage will have to come down. It isn't necessarily a bad thing, and I encourage you to try a ton of different settings.
It looks like your box come with a charging cable, so you can charge a battery in there directly. For external chargers, the nitecore i2 is awesome! It was recommended to me some months back, and has definitely been a fantastic work horse. 2 battery slots, and they are available on Amazon for usually between 10-15 bucks.