QE don't release any of their past papers and around 160 places are avaliable for students with academic ability & 20 for music.
The academic route has two sessions of tests,with the first entrance exam taking place in December and the second in Jan.All
canadidates ( in 2009 there were 1242 applications for places in Year 7) sit the first round but then only the first 500 are called back.
The first round is the usual verbal and non verbal reasoning.With 80 Questions to be done in 50 Minutes and multiple Choice.Where the non-Verbal Reasoning has 40 Questions to be completed in 20 Minutes but in sections of 10 mins and is also multiple Choice
Second round-Maths:50 Questions in 50 Minutes and Multiple Choice
English: 49 Questions in 45 Minutes with there being 1 long and 1 short comprehension. 2 sections of grammar in mutilpe choice.
All the scores at Q.E are standardised,so the school takes into account the age of the child when they are sitting the test.
Do you know what levels your son is currently at? I think the maths will tend to be tricky due to the timing.
Also one book I've always seen being recommended for this school is First aid for English. Which can be bought from here,if you haen't got it already. http://www.elevenplusexams.co.uk/books/