Factual error: In the ep in season four where Victor drifts ashore, someone calls the police officer at Gabrielle's home and informs him that Victor has been found. The officer answers the call, listens for about one second and then hangs up. In that one second he's gotten four sentences of information to pass on to Gabrielle about her husbands whereabouts. There wouldn't have been time to tell him so much in so little time.
Factual error: When Gabrielle becomes a widow she marries Carlos again in front of a priest. But the Catholic Church doesn't admit divorce, so in their eyes Gabrielle and Carlos were still married. They should have repeated a civil wedding, since only the civil effects of marriage were ended with their divorce.
Answer: Kayla was sent away in episode 16 (The Gun Song) in season 4, after falsely accusing Lynette of child abuse. She now lives with her grandparents - probably Nora's parents.
I'm curious why we never see her again, why she never talked about, and why Tom never mentions visiting her.