Sorry for leaping in, but Hugo is travelling today. The sequence
"\x02\x00\x01\x40" is 0x02 for read, 0x00 for the start address, 0x01 for the address increment, and 0x40 for the number of reads (64). See p31 of the datasheet.
Yes, you send as a string the data the component (whatever it is) expects. In this case that’s the command plus three bytes of data, but it might just be a register address, a different comment, or an address plus further data. The crucial thing is that you just provide a string of the bytes and impOS does all the work sending in in the correct way.