Is there a survey of the field of quantum automata? I'm looking for a survey paper of the important concepts in the field of Quantum Automata. I've found Quantum Automata Theory -- A Review
 by Hirvensalo, but it sounds too succinct to grasp the topic.
Is there a quite comprehensive survey on the topic of Quantum Automata?

Also, could you point me to the essential literature about the topic?
You can check the recent survey by Ambainis and Yakaryilmaz: Automata and Quantum Computing. It is comprehensive and points the essential literature with some open questions.

Moreover, here is a list of papers published on quantum automata until 2015.