Aren't some Lensbabys fixed aperture devices?
I think even those that are variable aperture are a manual twist on the front, with no electrical connections to tell the camera what's going on?
Sorta rules out using aperture priority I'm afraid.
So Lensbaby always = "Manual" as far as I know.
Also, I haven't seen a detailed spec for D3200, but I suspect that it doesn't have a focus motor in the body, like the D40, D60, D3000, D3100, D5000, D5100, etc. don't - So that's another thing to consider with other lenses you may have too.