Hi Pointytoes22
There isn't really an average age, I took Grade Five when I was 14 but was almost 20 when I passed my RAD Intermediate. You might be older than the other girls in your class at your school but may be younger than others at the same level at a different school so don't worry too much
A couple of years ago Central School of Ballet had a document on their website detailing 'essential' and 'desirable' criteria for auditionees and they asked for a knowledge of vocabulary at Advanced Foundation level. I have a feeling that when I looked recently they had changed this to Advanced 1. Of course, at the end of the day, vocational schools are looking for potential and talent so exam are to a certain extent completely irrelevant.