dirty language is the same as vulgar language. Words considered rude, or swearing is dirty, or foul language

literally means by the width of a hair. Often when something very nearly happened, or very nearly did not happen we can use this expression to emphasis how close something came. 'By a hair's breadth' is also commonly expressed as 'by a whisker' or 'by the skin of your teeth'.

If you are looking for one word adjectives, I would add inflexible or stubborn.

They mean the same thing, but sometimes word order can be used to emphasize a point. In this case however, word order does not make any obvious difference. One important difference to note is that while we normally omit the definite article in front of countries, it must be included in the case of Chinese mainland. We should say: I wish to travel to the Chinese mainland. I wish to travel to mainland China. You should avoid using China mainland, since it is poor grammar.

a wealthy bachelor. In response to the comment below, I removed the world old. This expression implies someone who is of mature age, that is at least not very young

The sentence is correct but a little ambiguous. Instead consider: We are not thankful for all of these mercies granted by our Lord. This is more direct and clear.