1. If the simulator can not receive information (pointcloud) from the valodyne lidar, make sure that you have the IRI package "iri_velodyne_lidar_bringup" typically inside "ranger3d" folder. If it is not the case, you can download it from https://gitlab.iri.upc.edu/labrobotica/ros/sensors/ranger3d/iri_velodyne_lidar_bringup.
In addition, make sure that you have installed the "velodyne_gazebo_plugins". If it is not the case, install it with: