You can use the plastic pot as a bonsai pot I have one that is similar but you can't use the vase that it's in , when you water it you have to water from above until a steady flow of water comes out of the drainage holes , it shouldn't stand in water for long or the roots will rot , trees absorb the water while it is evaporating not when the roots are sitting in water so it is essential that the soil dries out , not completely or the roots may dry out and die . What do you mean by the leaves turned choppy ?