In edinfestivals I'm listing all the events at the Fringe that are free. So far I've only gotten to children's, comedy, and dance/physical theatre, but the rest should be up within the next day or so. Some of them are ticketed but many are turn-up-and-enjoy.

And Sunday is the festival parade, starting at 230pm.

As for being fed, cairmen had an entry not long ago asking for suggestions about getting food cheaply, which might hold some useful information for you.