Ellie has been dead for over 40 years and modern concepts we take for granted are alien to her, such as the idea of the internet in issue #3 of I, Zombie. Ellie as well can only travel to places in which she traveled to when she was a live, as explained in issue #2, this limits where she can truly travel.
She is the Ghostly friend of Gwen Dylan. She helps Gwen settle the unfinished business that she gets after she eats brains.
Before she was a ghost she never been anywhere before. She never left her small little town. Right when she was going to leave a explore the world as she was getting on the bus she died and became a ghost. So now she can never travel the world like she wanted to because ghost could only go places they have been when they were alive.