You should not send more than 3-4 packets per second and make sure to send self-sufficient information, so you can reconstruct the necessary part of the scene based on the information you have. If one packet gets lost, then you should be able to get latest information from the next packet. Plan your dead-reckoning accordingly to interpolate the frames between packet reception intervals (linear interpolation, cubic splines, etc.)

I would recommend that both server and client keep sending packets. If no useful information is to be send, just send acknowledgement. This way, if client and/or server does not deceive anything within some time interval, it assumes that the remote party has been disconnected.