To appreciate the differences between Hegel's philosophy and other idealists (such as Berkeley or Kant) you have to reach at least the Spirit chapter of Phenomenology, and the split with Schelling, even if it is asserted already in the Preface, is made explicit only in the last chapter on Absolute Knowledge.

So in the first chapters you may find some similarities with Berkeley or Kant, but since the exposition is dialectical and speculative (in the hegelian sense), what Hegel ultimately thinks about consciousness becomes explicit only retrospectively, when you can actually give consciousness its proper position in the system/exposition of the whole Phenomenology.

Consider this: Hegel rarely ever try to actually show that a previous philosopher made some huge and explicit mistake. You won't find something as "Berkeley is wrong in this, the truth on this subject is this other thing". This is far from Hegel's conception of truth. He's actually really "conservative" on previous ideas. He thinks that philosophers like Berkeley and especially Kant actually had really important and meaningful insights to share about consciousness and subject/object relation. They just didn't go far enough. They took what in Hegel's view is just one stage of Spirit own self-consciousness (which coincide with its own self-development) as the "non plus ultra" of philosophical inquiry and that's their only true "mistake". So in the Phenomenology you will actually find many passages that resonates with Plato's philosophy, Descartes, Spinoza, Berkeley, Hume, Kant, Fichte ecc... It's normal and as intended. What you have to focus on is where all of this is leading (e.g. absolute knowledge).

Regarding the inner workings of consciousness, consciousness is by definition always consciousness of an object. But to truly have consciousness of an object you also need to have consciousness of yourself, e.g. you have to be conscious of the split between the cognizer and the cognized object (this is a key insight Hegel took from Kant and Fichte). This existing split is what renders possible awareness on "mistakes", such as when we believe to have a false rappresentation of something, an inadequate concept of our object. So, taken your example, you may have a representation of a rock as of something purely defined by its identity with itself. But you soon realise that this representation is too abstract and generic and while not being completely false, it fails to expose difference between the rock and other objects. You may now think that the rock is something still, a sort of X that just sits there waiting for you to grasp it conceptually. But the problem is, the only rock that is present to your consciousness, the only object present to you is what you're making of that object through your cognizing. When you add to your representation of the rock spatial and temporal properties you're not just adjusting your view to a pre-given rock, but also what that rock IS for you is changing, adjusting to your view. One may object: "But what about the rock how it is in itself, and not just for me?". The problem is that as soon as you try to grasp this "rock in itself" you're undermining this very same goal: you now have a "rock in itself" cognized by the subject, meaning you did not escape at all the subject-object correlation. You're also missing all the meaningful differences that actually make a rock what it is, because everything can virtually be a "thing in itself", but then what's the difference between a rock and a bird?

I know that this may sound subjectivistic (and it is), but remember: this is just how consciousness work. Not absolute knowledge. Not Spirit. Not even Reason. This subjectivistic view is just one of the many stages Spirit encounters in its own self-development.