The kamado BBQ is fired exclusively by charcoal, the use of briquettes is strongly discouraged. Briquettes are made of pressed residual materials which can give off unpleasant flavours. These attract in the ceramic and can later give off unpleasant odours and flavours to your food.
There are many types of charcoal on the market, each with its own characteristics. One type of charcoal is more suitable for burning hot and short, the other for burning long and at a low temperature. As a rule of thumb, the harder types of charcoal burn at a lower temperature and last longer, and vice versa. Also, each type of charcoal gives a unique flavour profile to your food.
If you are in doubt, the Grill Guru Oak charcoal is a good idea. Oak wood is in the middle of the range of charcoals, it lights up quickly and gives a delicious flavour to your dish.