I can't complete Waking Nightmare, every time the priest dude and I go into the temple, he tells me to hold on and shoots a flame spell at the door, which I suppose makes the thing open somehow, but nothing happens. The priest guy though proceeds to try to walk through until he eventually just transports to the other side. Leaving me on the other side unable to go anywhere. Anybody got an answer for this?

You can use a console command to get a quick solution: Just click on that barrier door in front of you, open the console and type "disable". The barrier should vanish and you can proceed. But I suggest to load a previous save, just to make sure, nothing else goes wrong (Waking Nightmare is notorious for bugs).