3) For the "depth of field" lens is there a way to change the default focus distance of 2.5m so you can fine tune which objects will get blurred or not for being out of focus?

From version 4, you can change that distance by setting the com.eteks.sweethome3d.j3d.PhotoRenderer.lowQuality.normalLens.focusDistance or com.eteks.sweethome3d.j3d.PhotoRenderer.highQuality.normalLens.focusDistance System properties (i.e. these changes will act as if you set global variables).