The boiling is both to kill off what's in it and to release the tannins from the wood. If you don't boil or soak before putting it in your tank you'll have an aquarium that looks like iced tea in a couple weeks.
10g Heavily planted - 1 mating pair of Apistogramma Cacatuoides "Orangeflash" and a whole lot of MTS
The boiling will also help it sink....if it's been outside in the air that long it'll float like a champ. I just put a piece of lake driftwood in my tank, mine was too big to boil so I just poured boiling water over it many times and also soaked it in very hot tap water for a long time.
If it does leach tannins they won't hurt your fish, it'll just discolor the water, and some fresh activated carbon will help remove the color.