no they are not expecting people to vacate, they expect many will simply pay up, and if they can't they will be evicted, perhaps not immediately, but you will be if you don't pay the rent. Just like anywhere. This is why it's a mess, brought in pretty quickly, no options of where to move to, and few single occupancy places, those that are are already taken by singles...
i can totally understand the principle behind it, this idea that it frees up space for families, what they haven't said or really bargained for is where do those people move to. And that it won't, as they have admitted, be a welfare saving. I can't answer all your points simply because i dont know them, am as much in the dark as anyone, i only had a rent increase letter two days ago.