The characteristic function of the Heston model is known in closed form. To obtain the option prices you have to perform numerical integration though.
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.139.3204&rep=rep1&type=pdf
you can also check the already asked (and answered) question
Problem on Characteristic function in Heston model
which refers to this paper
Duffie, Pan, and Singleton (2000)
Now regarding your original question: here is a reference for options on variance which seems reasonable to me
Pricing Options on Realized Variance in Heston
Model with Jumps in Returns and Volatility
they price a number of vol derivatives semi-analytically where only a numerical integration is necessary. This should help you