The controller only sends one packet every program loop, which means you only get all three roughly 13 times a second.
The interlacing means that although each packet is received the same way, the data it contains could be that of any of the three data frames described. The only way to figure out which information the packet contains is to read the control bytes.
Lastly, bit 7 is the MSB and bit 0 is the LSB.
Hope that answers your questions.
