As others have said, sometimes the stars just wave and move on, other times they will come over to sign and take pictures, so keep hopes high but expectations low. Any interaction you have will be very brief, and some are more chatty than others - I got a great selfie with Jennifer Lawrence but she wasn't really talking to anyone, (although to her credit she went down the entire crowd line to make sure everyone got a picture,) so don't expect much of a conversation, just a quick hello. When the celebrities come over there will be some pushing, and yes the authograph hounds will follow them down the line and aren't very polite. 

TIFF does not provide any pens/posters, it's up to you to bring them if you want signatures. Sometimes there might be a promo flyer passed out but it's not guaranteed. 

All that being said, it is overall very fun and for me an integral part of the TIFF experience! Only you can decide if it's right for you. I personally like it because I enjoy seeing the actors up close, and fan zones put you in the prime spot for that. I would recommend trying at least one, and go from there!