I use mega 808's from ikenvape and use it with the j-tank. It's much longer than the j-tank, but it makes it easier to screw onto my battery. I'm waiting for my m1a1 tank from notcigs to get here so i can see if it fits that.
I punch my cartomizers with a hammer and nail. Been working pretty well. You basically poke a hole through the side of the shell towards the part of the carto that will be at the bottom of the tank.
I don't understand how tanks really work besides when you take a draw it sucks in a bit of liquid through the hole. The rest is magic to me. Haha