What is the difference between STAFF and STUFF as personnel? What is the difference between STAFF and STUFF as personnel?

Why is the word used in the singular? I read in a book: "What are their names and occupation?" Can I use 'occupationS'? Is it correct to use 'occupation' in the plural? Is it natural?

the conditional construction If you want ....., you might like to..... Can this conditional construction take place? I am confused by the modal verb of the past tense.

About countries What is the most beautiful country in the world? It's not easy to answer this question. The beauty of countries may be various, from architectural to natural. As well as people and their mentality to be a part of this notion. As you can see I expanded the notion of beauty in this matter. So it would be a long list of countries. And this list would be much longer had some countries not suffered from wars (did some countries not suffer ?). I haven't been to any countries but I judge about this on TV programs.

Which of these words (engaged in, busy with, occupied by... or some other) should I use? Most of their pastime is BUSY WITH testing and using mobile gadgets, applications and internet surfing. 1. Which of these words (engaged in, busy with, occupied by... or some other) should I use? 2. Is the sentence grammatically correct?

Can I use "when"? From the moment (when*) you told me your story... * - would it be appropriate to use "when"?

Please check my bathroom description My bathroom hasn't a square form; it would be so if one corner wasn't beveled. Just in this wall there is the door. So it has a five-corner shape. Before I go on, I must say that this bathroom needs a renovation, I'll describe this process later. For the time being, the room is as follows: as I already said, the door is in the beveled wall; to the left of the entrance, on the wall, there is heated towel rail pipes of this is going to the closest corner that is opposite the entrace on the left; in front of the entrance, on the wall, there is a towel plastic rail, a little to the right of it there is a mirror... to be continued...