All bonsai trres except for succulent ones should be watered the same way. Once the surface looks to be dry, use a fine straimer and water abundantly over the whole surface area until there are a steady flow coming out the drainage holes. The excess water cannot be collected in a tray, it must be drained away.
I do not know the species in particular. But remove dead leafs and wood do not really help a tree. It maybe make it look better for the time beeing. But there are also a risk that you cut into live wood and hurt the tree more.
There are no quick fix for dieing trees. All you can do is focusing on watering, wait and hope. But really, this looks like a lost cause to me.
