Well in the episode where Lois and Clark go back to stop Tempus from killing baby Clark when his ship lands we see that Schuster's field is indeed just a field with a fence around it. As was said it could still be called Schusters field after the original owners who may have left town or died out over 100 years ago. In small towns once some one starts calling somthing by a name it seems to keep that name forever.
As for Mrs. Irig's name we do see her alive in the story Lost & Found I believe the name is where Lois gets lost in the snow storm and Clark finds her. Don't remember what is was but if you like it maybe you can borrow her name from there.
