has to be removed to either repair the seals or put in a new rack. The engine does not have to be removed for this repair. There was a posting a year or so back on how to replace the gaskets (sorry, don't have the link handy). If I was doing this job I'd just get a replacement rack and call it a day.
The oil pressure sensor leak is pretty easy to fix yourself. When I did mine I replaced the sensor too, since I was in there already.