Yes bonsai trees need to be watered frequently as you can not let them dry out. When watering, rather than pour water on top, I find it is best to use a small bucket or tray and soak the bonsai in an inch or two or water and let it sit anywhere from 5 minutes to 30 minutes. This provides the perfect amount of water!
Since your never home you might be better off with a silk bonsai tree
Or give a shot at growing cacti as they require very little care- just sunlight.