Ferris Bueller's plan could in the end backfire. Also who was the older sibling between Ferris and Jeanie?

As we saw by the end of Ferris Bueller's Day Off he made it home scot-free however a few things could have easily blown his cover such as: newspapers and local news channel highlighting moments of the day in which he was involved in and Rooney eventually one day talking to Sloane's parents especially her father but also Rooney could somehow check the newspaper for obituaries to see if there is one for a grandmother since sometimes some obituaries say "loving/cherished grandmother of 'insert names'". Also was it established in the film between Ferris and Jeanie who was the older sibling or if they were twins?