@johny723, the points don’t really need to be quite far, you just have to make sure that the boundary of the resection is not inside the parenchyma; leaving a small margin out helps making sure this effectively happens. For visualization purposes, you can (1) compute the distance map, (2) select the newly generated distance map for the resection and (3) mark the “Preview resection” box. This will cut off the excess of the resection for a better visualization.
In the volumetry section of Slicer-Liver you can use the “Generate Segments…” button to generate the segmentation with individual separated segments. Here is a picture leveraging on all features you ask:
