Same here! You should read If on a winter’s night a traveler by Italo Calvino if you like books within books. (Ironically, it’s told in second person half of the time.)
Interesting theory.
No problem! You haven’t missed it since the question hasn’t been asked/answered yet.
Yes, there will be several ROs (and, lucky for you, Icarus is one of them!) But only in the book-half.
Mainly because The City Child is around 12 years old and the only other characters are The City (which is a city made of metal), Mentor who’s late 20s early 30s, Nikolai who is around 17, Rosie who’s 8, and Miss Julie who’s also late 20s-early 30s.
But within Icarus Sun there’s 4 ROs:
Icarus
Cynthia
Copper
Lorraine
Or if you chose to not romance anyone that’s good too, having an RO will add to the plot some but it won’t take away anything. And some characters will be harder to romance if you chose certain options that don’t pertain to romantic intentions. (But that’ll be pretty obvious, since a lot of these characters have conflicting goals, such as Lorraine and Icarus. If you tend to side with Lorraine it’ll be harder to romance Icarus and vice versa.)