The festival organizers expect the Keaton event to sell out, so if you're interested in attending don't wait too long to book your tickets!
There will be a festival pass (which includes tickets to all of the festival events). This is expected to go on sale in mid-December from Colston Hall (http://www.colstonhall.org). I do not know what the price will be for the pass.
In the meantime, those interested in purchasing tickets for individual events can visit the venue websites: