Hi Janine,
You can find release notes for all of the Audium flagship gateway adapters in
this post. In the Cisco CVP with Cisco DTMF release notes there is a detailed section about known issues, which should address most if not all of the questions you listed.
For CVP 4.0, please refer to
documentation posted on cisco.com, although there are no analogous gateway adapter release notes for that version.
If you have additional questions after reviewing those materials, please let us know.
Regards,
Vance