Ukrainians are motivated, down to the last person, be it senior, woman, or child. Russians, not so much.

That I can't answer unfortunately. My experience is with English books.

While the numbers line tends to indicate printings, I think it's also been used to indicate year. It could mean 1951.

If it's a really popular book, then it's most likely the print run number.

Well, there's first edition, then there's first printing of the first edition. You can generally determine if a book is a first edition by matching the publication year and publisher (found online) to the publication year marked in the book. Determining the printing could be tougher for older books. Sometimes you need to know specific things, like typos in the dust jacket, colour of the end boards etc.

It really depends on the publisher. Some are more detailed than others. Tracking of printings was not common before the middle of the 20th century. Then the Printer's Key or Number Line became popular and made things easier.

So you need to know when the book was first published, where it was first published, by whom it was first published, even before looking at the book itself to determine what printing it is.

Luckily having the internet as a resource really helps.

/r/BookCollecting as well.

There's no easy way. You need to know the order of publication, which tends to be, but not always, based on the author's nationality.

Then you need to find the original year published. Then check the book itself to see which printing it is (though it's not always indicated).

The further back you go, the harder it is to establish these things because publishers hadn't yet standardized the publication details page.