I have a flat top, I double clicked the top of it, and then sketched a single line one half inch offset from the side. I was able to then select that face and extrude so that there is an extension from the original surface. The problem I’m having is that that extrusion is part of the original top, but my intent was for it to be its own body. How can I make the new extrusion it’s own body?
The fundamental way is that you should create a new layer and activate it before drawing on the original body’s surface, that’s why we create new layers and such a feature is maintained in the App and almost all 3D modeling apps… In this way you will have each body separately without needing to split bodies, otherwise you would have all in one layer which means that they all belong to a united body.
Tip: when you extrude from a sketch on face at the end of the dragging a boolean option icon appears next to the dimension. If you tap on that, you can change it from “union” to “new body”.
Best reminder 
