Hello loger...I used google to translate Anver's answer :) However : You were right we have many dialects but in spite of that we can understand each other.As I know that's not only in Arabic so don't let that confuse you.For me I started to get my first language (dialect) from home and community but I get classical Arabic from school,media,books the matter is up to you if you want to use language to communicate with others then start with one of those dialects but if you have another purpose like you want to know about literature or islam then you should learn classical Arabic

Я когда-то начинал с классического, но вскоре перескочил на разговорный. Классическим можно пользоваться на различных форумах, но при непосредственном общении, пользы от него крайне мало. Быстро приходит разочарование, когда спрашиваешь что-то у людей на улице на правильном арабском языке, а люди от тебя шарахаются с ошалелыми глазами. И смотрят как на инопланетянина. Я уже это проходил. В Египте. Больше с классическим языком не эксперементирую. Выбор за Вами в зависимости от целей которые преследуете

I think Egyptian Arabic is the most spoken and understandable dialect.

Classical Arabic is no longer spoken , however if you learned it , all Arabic speakers will be able to understand you ,, But i recommend Egyptian Arabic because it's very common and most Arabians can understand it because they are influenced bu Egyptian media like Movies and series

no one talk classical Arabic. we only use it in writting (formal only) or sth like that.