Throughout the series, it is revealed that the students, the group in particular, have Sikowitz's contact details. In reality, students and teachers are not allowed to have each other's contact details.
It's unknown how Tori and Trina's parents can afford a nice house. Their father is a cop and cops don't really make that much in real life. It's unknown if their mother has a job or is unemployed. But there's no way the Vega family can afford a nice house on a cop's salary.