What you're saying is pretty interesting, because I think we all classified people in different categories when we were children, and as we evolved those categories evolved too. To answer your questions:

My classifications seem to be way too complex to explain, not even I understand them, but to put it simply, I think I classify between people who I get on well with and people who I don't get on well with. After that, it becomes a dichotomous classification and it just branches out. It's after that first classification that I see whether they have their shit together or not and what kind of person they are. What I dislike about my first classification, is that when I'm not sure if I get on with this person or not, I get confused and frustrated and I don't really know what to think of them.

Yes, definitely. They change categories and that becomes pretty confusing too. If they do, I normally tell myself that actually they were always in that category and I just wasn't able to grasp that. It's kind of rare that they change, but I had a friend with whom I had a fight and after that we never talked again. I guess it's simply because I had not realised 'who they really were'.

That is a good question, and one I could not answer. I think you will never stop understanding the models, because as you said, they are always changing. To be honest, I would say what is next is to start acting upon them. Once you understand a model, try applying it to real life. For example, imagine you classify a certain person as 'advanced'. Try applying what they do to your life, and experiment around to see if you perceive yourself as getting closer to this 'advanced' section.

It's just a suggestion, but I think it's a very interesting topic!