Load your wireframe into Photoshop. Copy it to a new layer (safety net) and save as wire.psd (second safety net) Set it Image>ChannelMixer. choose desaturate and see that you have a good contrast and continuous lines. Then sharpen the image with unsharp mask (start with some 500, 1,2 , 2). Then threshold to set to black and white. See that you have good, non-broken lines with the thickness you fancy). Now, with only this layer visible, go to the channels palette. The three channels are identical, so Ctrl/Cmd click on one of them. This loads the layer as a selection. Invert the selection to get the wireframe selected. Now go to the paths palette and load as a workpath. etcetc As for Illustrator: can't help you there as I use Xara for vectors and that has a bitmap to vectors convertor.

I have tried prudent planning long enough. From now I'll be mad. (Rumi)