Your question "does anyone know how many want to return?" has been answered. I do not have the reference now, but I remember it was just a few percent (no "threat" to Israel). The RoR is actually not about physical return, but about recognition of the misery and injustice done to Palestinians during Nakba and later. If Israel recognises this, the parties can speak about healing their wounds, but plain denial (compare Holocast denial) just increases the anger.
from the article: While Livni is polishing her wording