Are more render channels in the roadmap? These are quite important for compositing.
I totally agree. I wonder why they have chosen not to have them included already. My firm is thinking about buying vray for Revit att the moment, but the lack of the material id channel might be a dealbreaker 
Yes, adding more render channels is on the roadmap.
Is there a timeline for when additional settings might be released anywhere?
Unfortunately we cannot announce any time frame.
We are planning to release an update soon. I cannot give you more info though.