I was there like 1-2 weeks ago. He was very nice and signed my playbill. The security guard did say that he was only signing "The River" related stuff. He spent 10-15 min. with us in the blistering cold. I'm not sure if he would sign anything else if you did slip in something else to get signed, but it's worth a try!
went yesterday and successfully got sro tickets for this performance. even though the website said tickets were sold out, the lady at the box office said they weren't. went about every 2 hours and at like 12:50 ish, I was able to get one. It is really a crap-shoot to get them... but I got really nice sro tickets and the play is worth it!
I sat on one of the riverbank seats! The lady who was passing out the playbills said something about backpacks, but I didn't listen clearly to what she said. I kept my backpack pressed against the bench with my legs and it was fine. They'll let you know how to situate backpacks and small bags when they hand out the playbills.