where is the power steering leak, if its from the inner tie rods your looking at a new rack, if its the lines or pump let me know, I have those sitting in my garage and you can have them for free. I switch to manual steering so won't be needing them anymore.
changing the rack ins't that hard to do, and its always a good idea to get new innner and outer tie rods while doing so, and an alignment.
as for the rust - doors are not expensive so wouldn't worry about that, if its just a little
rust no biggy, just make sure its not all the way through the metal.
The milage is really low what motor is in the car??? is it a M42?