1) If that doesn't work to collapse a node, then I don't think there is a way.
2) node_object.destroy() should work.
3) You should be able to do it the same way as with GuiTextListCtrl:
PHP Code:
with (addnodebypath(i.name, "/"))
{
icon.clearall();
icon.drawimage(0, 0, "icon_image.png");
}
node_object.icon is a TDrawingPanel, same as rows in a GuiTextListCtrl.