The only common things really are the rear beam and ICV
Rust is hardly common, some people get it yes but its not common
I have had two saxos and a 106 and never had a rust issue
Gearbox is hardly common, they do go occasionally but thats the case for any car
Clutch is a part which wears over time/use like tyres etc so you can't really say its a common issue
Head Gasket is not common either, failures are usually to do with overheating or constantly pushing the car too hard. It happens but it's not common.