I fully sympathise with you. I think this is a situation that any teacher, experienced or not, would find difficult. I’m sorry that you are having such a bad experience in your first job. You have quite a lot of questions here, so I will answer them in separate posts.
First of all, in answer to question: Is this a normal experience for a first time teacher? I would say that this is certainly not the best way for students to learn. I’ve never worked in Greece but I have heard many similar stories about private schools that cater to teenagers and other people preparing for Cambridge exams. These cram schools just focus on giving the students exam practice. I’m afraid that your first experience is not optimal. As for students being unable to use the vocabulary you taught correctly, that is pretty normal. Students need to revise, review and use language repeatedly before they are able to use it correctly in free practice.
As for discipline or classroom management, it is never too late to start. True, it’s better to start out with clear classroom rules, but it is not too late to introduce them now. You can look through the helpdesk and other forums for ideas on this topic. You can take a look at this post for ideas on encouraging students to use English:viewtopic.php?f=2&t=13
As for the teaching methods, I’m afraid to say that you don’t really have much choice at the moment. Your employer has decided how the classes will be conducted and while you are working for her, you have to respect her wishes. This doesn’t mean she is right, or that you have to agree, but you may have problems with her if you don’t follow what she says. After you have spent more time in her school, when she knows you better and you have more experience, you’ll be able to suggest other ways of working.
I'll answer your other questions in another post.