Runs two 1.5V AA batteries, used to power the flash.
Here are some pictures of mine, taken 2010-08-10. Click on any photo to enlarge:
Good question. People report shooting 200 to 800 speed film (see reviews below). I'll post feedback from people here periodically. My first roll used in my LOMO Action Sampler with 400 in sunny conditions yielded very grainy results. If this is any indication for film in the PB, I would personally recommend lower speed (200). Check out the gallery for my first roll of PhotoBlaster film, shot on Kodak Gold 100. I think 200 sounds pretty optimum given the first results.
I started a poll sometime in October 2000 to March 2008 on the old Photoblaster Worship Page, here are the results:
ASA 100: 63 votes (38% of respondents)
ASA 400: 58 votes
ASA 200: 26 votes
ASA 800: 20 votes