The juice is fed through a hole in the cartomizer that you can easily punch with a hammer and nail. It is a simple concept and works perfectly. I recommend only punch 1 hole in the cartomizer as two holes let in too much juice. There are videos on youtube that explain how to punch a cartomizer.
As far as batteries go the AW IMR 18650 are the best (noticeably better than Trustfires). I use Tenergy 3.0 volt NiMH batteries for 6 volt
vaping. And so far the 4.8 volt NiMH are only made by one supplier (I get mine from Clouds of Vapor).
Hope this helps and happy
vaping!!!