First install kitti2bag. Follow the construction to create a rosbag.
Follow this to visualize the image and lidar points on rviz.
here is some source code of how to create ros msgs.
It is faster to encode the video stream to bytes (e.g. in mjpeg), then send the bytes, instead of sending an image array.
Here is a tutorial on how to create basic markers using python.
Use chrony to synchronize across machines.
tutorial