Haemophilia is not due "thin" blood. Haemophilia is a genetic disorder where certain blood clotting proteins are missing. It's a recessive, sex-linked X-chromosome disorder. And since women have two X chromosomes they are less likely to have two bad copies and are far less likely to have this disease.
The disease has nothing to do with the thickness or thinness of blood.
Rosewood asked Beatrice about the bookmark. She said that the metal part was lost.
Later the metal part was found at the crime scene.
Why would should take a book the the crime scene / or to a murder?