I've got it working fine with my Spark-supplied HG659b, no issues.
The only difference in my config that I can see is that I don't have "Use outbound" enabled.
I do have a static IP however.
I'm using a Vodafone-sourced HG659 with the Bigpipe firmware (previously Spark firmware) loaded; 2Talk VOIP is set up on the router and has worked perfectly from day one. While I was warned I may end up needing a static IP address, that's not proven to be the case. My settings are the same as in the OP's screen shots.
None that I've noted! I'm sure the interface was improved when going from the original Voda firmware to the Spark version (the router was a spare of of my parents), but can't recall any gains going from the Spark to BigPipe.
Did you have any problems with the 2.4ghz network? im the same as you, i have a modem from vodafone (same one) put big pipe firmware on it and the 5ghz works great but the 2.4 is broken. drops out, really slow, hangs on speed tests etc
Just wanted to add that I got setup with 2talk fine using a Bigpipe modem on fibre and the settings from the first post.