Hey man thanks for doing this :)
One thing though, question 12 a) iii) asks for z^2-z(conjugate), not z^2-(z(conjugate))^2
(Also sorry for the formatting.)
Edit: Looks like someone else beat me to spotting it ^^
For the simplest exact value, I'm pretty sure it's correct as long as the numerator and denominator can't cancel out anymore, i.e. factorisation of the numerator isn't required.