ReaddleDocs allows direct access to the camera roll, but I am not sure about getting them to the computer from there via Wi-Fi. It apparently doesn't let you see images in other folders, though. I don't have Readdle Flash Drive.
I do have Air Sharing (but not Air Sharing Pro). It does not give you access to the camera roll on the iPhone. I also have File Magic, another flash drive-like app. It also does not give you access to the camera roll.
I am fairly sure you will not be able to put things into the camera roll from the computer, but you would have no trouble adding images to the iPhone in other folders with any of them. And they all have their own file viewers for displaying documents and images. But I don't think that you will be able to see images transferred by any of them to the iPhone with the Photos app on the phone.
I am at work now and not where I can connect to a computer via Wi-Fi to check. If I learn something useful to you this evening, I'll return and update.
Edit: Another thought: Are you opposed to using a different photo manager than the native Photos? If so, something like SplashPhoto will allow you to manage your photos over Wi-Fi. But that one won't let you access the Camera Roll directly either.
Edit 2: Oops. Actually Splash Photo will let you access the Camera Roll and any other folders of images that are contained in the native Photos application. You can transfer them from there into SplashPhoto, which does sync to a desktop companion application via Wi-Fi.