Was the Word prior the Incarnation a self-conscious Individual?Yes or No question.
First what is a self-conscious Individual? When you ask about "individual" I say "No, He is not. He is "a Prosopon of the Trinity," and even that terminology is weak to truly describe the Limitless. When you ask about "self," I also say, "No! Because a self is created. He is uncreated. He is beyond self." When you ask about conscious, I say "No! He is beyond consciousness. Conscious is who you and I are."
In the end, the question you ask is actually invalid, because God cannot be compared to something that is known in an anthropomorphic sense.
What precisely got Incarnated of the Virgin and how?
"What" and "How" are mysteries. The Incarnation is a mystery. It cannot be explained adequately. We can only answer "Who." Because the "What" and the "How" depend on understanding the essence of the divinity of Christ and how it was united to the humanity, and since the understanding is beyond what any human mind is capable of understanding, then this question is also invalid to ask.