Obtain data from sensors and add noise to sensors in gazebo_sitl

I followed the instructions fromhttps://dev.px4.io/en/simulation/ros_interface.html and run these commands:

cd <Firmware_clone>
make posix_sitl_default gazebo
source ~/catkin_ws/devel/setup.bash // (optional)
source Tools/setup_gazebo.bash $(pwd) $(pwd)/build_posix_sitl_default
export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:$(pwd)/Tools/sitl_gazebo
roslaunch px4 posix_sitl.launch

I want to know how I can add noise to sensors and how obtain data from sensors. Besides, does it use only IMU sensor? Are there not other sensors (eg.GPS/mag/lidar) in sitl?
Thank you very much!