‘Should I still be doing this?’ That’s a pretty big question to try to answer during an hour long Fringe show in a small and warm room in Appleton Tower, but here is Susan Harrison doing exactly that as she takes audience members on a whirlwind adventure through many of her comedy characters, complete with sketches, songs and a great deal of audience interaction.   Very familiar with the fringe, often performing with Showstopper, the improvised musical, Mischief Movie Night a