LOL man... Really your threads sometimes... And those subject lines...
My personal take on your questions.
- Do they enjoy talking tot heir students about classical music? Wil they get angry or annoyed because of the lack of knowledge the student has about music compared to the teacher?
Yes I enjoy talking to my students and if they don't know something I feel it's natural, since I'm there to teach them...
- Will they get angry if I choose the piece I prefer and not the ones they want?
Depends on what you choose. If you decide to hit the Rach 3 (concerto) I'll probably just stop you. If your choice coincides with what I have in mind that you need then why not? If you just want to play pop songs (for example) it's fine as well, but I need to know in order to arrange the lessons accordingly. I tend to individualize every course for every student.
- Will they be annoyed if we just started grade 7 but I tell her that I want to do grade 8?
No, but I will think that you're only 14 and thus you are just taking things too fast. I'll tell you to relax, take your time, feel fine about your life, find a girlfriend (for example), and really try your best but donm't kill yourself. There's a reason why grade 7 is bellow grade 8.
- Will they be annoyed if I want to play a piece that is somewhat above me but I can practice?
If this doesn't get in the way of your normal routine then I don't think I'd mind. But it really depends on what work, etc.
- Do they enjoy teaching?
You're kidding right? I love teaching... And I think that most here do. There are the cases of teachers who teach becuase they failed to have a great enough career, but I don't think that's the case with most teachers.
- How do they feel about advance students?
Personally I feel much better with advanced students rather than with beginners. My communication skills tend to work better with 14+ ages rather than 7-9... I have younger students and they are doing fine, don't get me wrong (my kids are also around that age), but it remains that I prefer older students who are more advanced.
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That said a general advice based on your posts:
You ask SO MANY question about EVERYTHING. Your passion is a given fact, according to your posts. But take your time. You are 14, already rather late to be a young prodigy, so do the best you can to make yourself even better.
Don't rush things. You're in grade 7! Remain there for the year (or somewhat). You might be going faster but even if you're doing much much better than expected, grab on repertoire and treat it the best way possible...
Don't be anxious. Your teacher wants you to do the best you can and most probably knows what they're talking about. If you feel they actually DON'T know what they're talking about THEN start asking questions about all those issues (I mean being scared that your teacher won't like that you also like pop music? That he will be angry if you propose to play a work?)? This shows a huge fear about teachers...
Sorry for budding in like this. I hope you don't mind.
your so awesommmeee 
I wish my teacher was like you :P, my teacher barely even knows how much I love classical music yet :s or how much I love the piano