I have two of these units from Hobbyking and use them. Both record audio. Have recorded audio through fpv camera with built in mic or vtx with built in mic.
Not sure about fps but the video is smooth with the occasional tiny 'jump'. Sort of like a couple of frames was lost during flight recording due to interference. Doesn't always happen.
AV1 is used to display menu as well as video playback in addition to received video. AV1 normally has the top horizontal pixel and or the bottom horizontal pixel with a black bar. The black bar is not that obvious when flying unless you keep looking at the edges of the video feed. And sometimes, the screen has very slight 'shivering'.
AV2 is smooth without AV1 issues. I fly with AV2.
The record function will cause the external red led (next to the record dial) to blink so I don't need to check AV1 for status. Just don't press and hold the dial as that will move it to menu mode.