Thanks a lot, very good explanation.
I am quite surprised that job is not used in informal or slang talk.
In Czech we use it quite often as informal word even older people use it. It has its own form in our language "džob" where dž sounds exactly same as j in job. But both forms job and džob are understood in the population. It was used even in the years of socialism as informal word used when talking with your family, friends or people your age. But it has to be used the right way in other case it might sound weird.
Again thanks for your very good explanation.