I am using QBChatMessage. How can I get the sender's profile photo and user ID?

You can use    message.senderID   to get sender’s user id.

In order to get an avatar do the following:

How to update user's avatar http://quickblox.com/developers/SimpleSample-users-ios#Updating_a_profile_picture_.28avatar.29

- Get users with IDs:
http://quickblox.com/developers/SimpleSample-users-ios#Retrieve_Users_by_IDs