Settings for AVCHD 2.0 Progressive compliant file, playback

[Selur]

For 2-pass encoding with 24000kbps setting and Max Bitrate set for 25500kbps, is it enough freedom, headroom to maintain an average 24000 birate that will be limited to 25500?

Probably totally depends on the content.
A bouncing bit rate and a constant average bit rate is usually what you want,...
My guess is that 2pass encoding should be able to handle it, but test it and see whether it worked or not.

Cu Selur