Also, forgot to add. LiPo chargers say 6 cell etc. Does this mean it can only charge a LiPo battery up to 6 cells? or 6 cells at a time?
It's not the number of cells, it's a measure of the discharge rate of the battery. If you have a 1600mAh battery and it has a 1C discharge rate it will discharge at a max of 1600mA. If it has a 20C discharge rate then it's 20x1600.
IIRC you want a 25C, it's the optimum discharge rate AFAIK. 30C is a bit too high, and 20's a little low.