Hi,
Sounds interesting. While I might not be able to contribute directly to development, I thought I’d share my thoughts at least:
First question: I think the idea could work. The overall implementation will likely depend on other variables (?). For example, someone approaching the game with a story focus will tend to end up with something different than someone approaching it as a physics game (apologies if this subject was already covered in the post).
Second question: Unity comes to mind, though there may be other good options too, like Unreal.
Third question: Starting small to learn the basics can be useful. Without that foundation… even large projects can sometimes struggle.
Edit: I kept my answer a little brief for the subject, but am willing to expand on the individual points if needed.