There are different kinds of language schools in Turkey.  If you want to teach on a University level, most likely a Masters degree will be required.  There are private language schools that may not be as particular as long as you have qualifications they are looking for (and they will vary depending on the school). 

Knowing Turkish would be very helpful.  Although, I teach english as a second language in the evenings and I have a mixed class of spanish, vietnamese and arabic speakers in my class and I speak intermediate Spanish (at best).  It is very difficult to teach a language to someone who doesn´t share a common language but not impossible. 

why ?

İs that the 6th pillar of Islam, or what ?

Arabic is necessary for every muslim because of reading Quran and praying , praying should be in arabic language

i am not a Arab, but i know here in the states arabic language is very useful because the middle eastern region is very important politically and to be able to understand arabic is a good thing. my friend for example, CIA wanted to hire her because arabic is her mother tongue, but she refused of course. also since turkey is in the middle eastern region, from economic point of view it is good to learn arabic.

but as a muslim, although it is not compulsory to learn arabic, but to improve your knowledge about islam and to understand and appreciate the Quran better by learning arabic. When i was younger i always pondered the words of the Quran, something sounds like "even if you bring the whole world together, you cannot even make a sentence better than the Quran". To me it didnt make sense (because i didnt know) but after learning arabic i understood why the Quran is definitely a miracle.

That is not a valid point of discussion. The holy book itself does not make a Master´s degree in Arabic mandatory for Moslems to read Kur´an. You can read prayers in your own language; in fact, if you do not know any prayers that should not stop you from praying, you can address God straight fom your own heart.

That Kur´an was sent in Arabic does not make Arabic a holy language. You can find some of the best phornographic literature or obsene language in Arabic too.