The third coin in the OP (the two bottom bictures) is, unfortunately, a modern replica, mass-produced for Feng Shui purposes.
The first coin is, as arok stated above, from the Song Dynasty and is roughly a thousand years old. This coin is from the Yuan You period (AD 1086-1093). It appears to be genuine (though see my final paragraph for a warning).
The second coin is indeed a Japanese "trade copy" of a Song Era design. The Japanese coins date from the mid-1600s.
As for your more general question: "Chinese cash coins" were produced throughout eastern Asia. Besides China itself, there are coins from Japan, Korea and Vietnam. All these coins have the same alphabet of "Chinese characters" on them; all these languages can be written in the same script, only they are pronounced differently. The second coin identified above, the Japanese trade coin, for example: the legend reads "Yuan Feng Tong Bao" if you are Chinese, "Genho Tsuho" in Japanese, and "Nguyen Phong Thong Bao" in Vietnamese. They all mean the same thing: "First Abundance Current Coin".
There are websites you can go to that identify the ones you're most likely to encounter: Chinese coins of the Qing dynasty (roughly AD 1600-1900). But there's a bewildering variety of "cash coins" out there if you consider all sources.
Vietnamese coins add a particularly confusing element to the mixture, as back in the 1700s, the king of Annam (central Vietnam) allowed the private production of cash coins. These "unofficial" coins had a wide variety of designs, and frequently copied older Chinese, Japanese and Vietnamese coins.
So your first coin may indeed be a "Vietnamese copy" of a Song Dynasty coin; the easiest way to tell is by size and weight. The Vietnamese copies are almost always much smaller and lighter than the originals. Indeed, some Vietnamese cash coins are nicknamed "floaters" because they're so light, they easily float on water.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis