How does your Premiere Pro Integration work?
We have a panel that is embedded in the Adobe applications. The panel is shared between the supported Adobe Applications. More information is available in our documentation
Generally our proxy workflow uses the h.264 low bitrate format that we use in our web frontend. This has certain restrictions as it's in an MP4 container on number of audio channels and tracks. It is also possible via the API to create a new format that can be used as a proxy and this can be any codec or container format that you like.
Generally proxy support should be limited to video, as that is what is supported by Adobe themselves. It is possible that it works for audio and other types but you might experience problems when it comes to switching them within Premiere using the native functionality.
You should also be aware that you should only proxy with material with the same layout of audio tracks as the original material
We don't restrict the files by type when you try and open it in the Adobe Applications. As over time the formats and types of files that the Adobe apps change we let the host application handle whether it can open the file or not.