Quote - Doesn't the magnet and base  have to be large enough to enclose the area you want to manipulate? I know the magnet zone has to be, but doesn't the magnet base and magnet have to be too?

No, only the zone size and position is important for what's affected when you transfrom the magent relative to the base.
When you add a magnet Poser sets the base so that it's approximately as big as the group your attaching the magnet to, and centres it on the group.
This isn't always convenient as the magnet and base will probably get in the way of setting the zone correctly, and is especially awkward when your using more than one magnet on the same group.