i´m thinking abour upgrading my ipod 4g from ios 5 to ios 6.x. which version of appradio extensions, appradio app do i need to get everything working?
Currently, if you upgrade to IOS 6.x you will have no touch support for unsupported apps on your radio.
In short, you can not upgrade and get "everything working.
I received my AppRadio 2 last night, and since I had already upgraded to IOS 6.1.2 with the Jailbreak
I added http://mikedecaro.com/repo/ to my Cydia sources and installed Appradio Extensions version 2.0.1-42 in Cydia.
I also installed the Pioneer Appradio App version 2.2.0
This setup, as far as I know, (after reading this entire thread) gives me all of the functionality currently available
in IOS 6.x
Other members are welcome to correct me if this is inaccurate. 
As an additional note, My AppRadio 2 (SPH-DA100) is running Firmware version 8.17