About the "on-rails" gameplay.
I think that the character does not move by themselves alone. You probably push the analog stick to move them along a set path, back and forth, like a train...
When you are in the big hall you will probably have the freedom to move around freely. But whence you get to the stairs, the character will probably lock on to the "tracks" if you know what I mean.
Well if they were smart they should have done it that way.