Even in America, "ain't" is seen as extremely slang. Many even argue whether it is a word or not. People stereotype American's from the country (the rural farmlands) as people who say "ain't" and don't know english. In general, "ain't" should be avoided. Instead, stick to words like "isn't," "won't," "or "hasn't."

Although some Americans might disagree on whether "ain't" is slang or not, I think we can agree that for a non-native speaker it should not be used in daily speech. It seems from your post that there are some other things you can be working on. For example, instead of saying "Whether is normal if I be use 'ain't' in my speech?" You should say, "Would it be normal if I used 'ain't' in my speech?" Better to focus on those things first. :) In America we have a saying we are taught in school (at least most of the people I know have been taught this), "Ain't ain't a word, and I ain't gonna say it!"

Ha ha! Now you've opened a can of worms. Where I'm from, it is a part of the language. Less so in other parts of the United States. It is very colloquial. It is the way we talk when no one is worried about "proper" English. Or, when we ain't worried about speaking proper. My advice to you would be to avoid it for now.

No! That's all right! Thank you for your correction)

"Is it normal if I use "ain't" in my speech? ...or will it be better if I don't use it at all? Is it typical for colloquial speech?" Sorry to be picky, but "If I will/would..." is never used in English, unless you're trying to be extremely formal (eg. writing a presidential address, or writing to royalty). Just keep the "if" part in simple present/simple past/past perfect. That's all you need. :) Modals only sit in the other part of the conditional, otherwise your sentence looks extremely jumbled.