This is all very good information. I would add the tool "inspectrum" to the list of utilities that are useful for understanding signals. It can even decode the FSK data stream into 0's and 1's for you.
I've set out on a similar project for Elster brand water and electric meters. I started by writing a library for use with rtl-sdr
https://github.com/shaunhey/ea_receiver, and now I'm working on using an RFM69HCW module to receive the same information. I previously tried with a TI CC110L module, but had trouble actually receiving anything, even though the meter itself uses a CC11xx chip (may have actually had a bad unit), but the RFM69HCW module works fine. Unfortunately for my use case, the data (including length prefix) is xor'd with 0x55, so I can't use the RFM69HCW's built in variable length packet processing, and the meter uses multiple sync words, one of which triggers a 4x increase in data rate and turns off manchester encoding, so there is a possibility that I won't be able to use the RFM69 packet mode at all.
I'm curious, which brand of water meter are you reading? Have you checked to see if it is supported by rtl_433 or rtlamr? I have an itron branded gas meter which is supported by rtlamr.