You cannot add components to the built in editing panels. However you can have ten Custom Panels. You can easily recreate the Audio Panel on a Custom Panel with added fields. A custom field can be pretty much any Yate field or named comment, UDTI or UDURL. If you store the individual VBR, CBR values as UDTIs they can be displayed. The values are static and the space overhead is virtually zero.

However, on the standard Audio Panel, you will see the bit rate in the Audio Information panel whenever a single file is selected.

No reason why you can't. You can even write a tiny action to extract the value from the property if you want.