Unreal Engine is still used with StageCraft 2.0 but not as the “final frame” renderer which is now ILM’s Helios renderer.
According to the article Unreal is used as a DCC application alongside Houdini or Maya but the actual engine is now Helios.
Yes, but if you know what these applications are used for and read between the lines Houdini is used for simulations, Maya is used for (by hand) animations and UE is used for scene composition.