>>4982ps1 audio does work, albeit through a separate exploit found in a ps1 classic came (I use Tekken2)
There are some limitations to the psp firmware on Vita, namely nothing ad-hoc works. Both the wifi and usb connection are always controlled by the Vita fw and not the PSP fw..
The good news is that the psp browser works with the Vita's mobile connection so you can download zips, iso's, etc andmanage them with Filer.
No actual modification of the Vita's fw has appened, though. TN-v10 is actually a savegame exoit for a Vita psp game from psn.
And, sadly, you missed the bus. All the exploited games were pulled from psn a few months ago when the 3.20 update was released and the Vita scene has been dead silent since then.