The Position is the insertion point. So changing it won't change the justification from the upper-left to the upper-right, it will move the entire table.
But you can change it like this:
table.Position = new Point3d(x,y,z);
As far as changing the justification, I'm not sure. Tables are subclassed from Blocks, so you might be able to set an X-scale-factor of -1. Or maybe that FlowDirection property might help. Or maybe it's impossible, I don't know.