Just some advice Rob...
The rear window demister is fine with the tints.
When you've had your windows tinted, they do recommend not to use the windows for 12 hours just so that the film has enough time to dry.
The front side windows come out as well as the rear side windows. Remember that you have the dot matrix around the perimeter of the rear side windows and the rear windscreen. You will "never" be able to get a perfect/smooth finish. The air pockets take a while to dry out.
The rear window is left in while being tinted. If you have a rear spoiler, remove that and then put it back after. You'd obviously cut around the holes where the spolier fixes through the rear windscreen (if it's not mounted on top) and when you come to put it back, do the screws up quite tightly and then do them up properly a few days down the line. This will prevent the film being twisted in with the screws.
Remember to replace the internal draught seal on the front side windows because if you don't, the film will become scratched and you'll have to do it all again.
I myself would never have the time or patience to tint my own windows. I paid £125 to have mine done
Hope that helps.