I think that a reason that the dinosaurs can't interact with rocks is because you can rotate them on all 3 axis, therefore there's no place for an animation to be specifically scripted onto a rock without clipping issues.
I don't know, but I can only suspect they might try attachment points with data tracking which way is up when the object is placed: that should at least allow pterasaurs to perch.
Yes, and PK still hadn't been released yet. I think some of the developers admitted that it will take longer than expected. They also cut the number of animals the game will "release" with down to 12 last time I heard. I put release quotes because it will actually be an early access release and not a full release.