1- Yes and I think it is the 3rd to 7th. The last 999999 reading has a different meter ID. The meter ID could use part of byte 8
2 - The column headings are my best guess. I am more sure of the reading because you can see the bits change but still a guess.
Yes I think the data is encoded and DC balanced. If you add up the 48 bits for readings there are always 24 1's and 24 0's. Same for the 48 bits starting at 3rd byte. The first two bytes and last three bytes also have the same number of 1's and 0's.
Yes there are many options for encoding (Manchester, 6b/8b ) prevent the long strings of 0's or 1's.
The 0 read bytes are interesting; there is a pattern in every other bit 001, 001, 001 or 110, 110, 110 through all 6 bytes
I did not look for redundancy and only a little at interleaving
In other systems the receiver adds bytes at the end for Error Correction Count, Signal Strength and then a check sum.
Thanks for you interest