Originally posted by BBear [*]When on Av Mode and flash mounted on camera, the shutter would lock at 1/50s. I thought something was wrong with the camera, but as soon as I removed the flash, Av would work normally again (shutter varying as Av was selected).
Unless I'm misunderstanding something, that's normal, even for the builtin flash. Remember, in flash photography shutter speed is largely irrelevant, since the duration of the flash is far shorter than the shutter speed anyhow. So Av mode tends to just set something like "1 / focal length" as your shutter speed, unless that would actually result in overexposure just due to the ambient light.
Sorry, I don't know anything about the AF540 in particular or wireless in general, so I can't help with your other questions.