Yes, the whole Formation moves, though whether the ployed column portion makes contact depends on if you have any deployed Units ahead of it. The ployed portion of the Formation could certainly end up not being in the front wave.

As to how many ployed Units fight: any contacts fight. I say this precisely, because after Order Conversions regular movement happens, and enemy Units you didn’t contact are likely free to move and may contact your Units even if your Units did not contact them. But keep in mind, ployed Units may only voluntarily leave the ployed column during the deployment step of Movement.