Unknown Chinese Coins

I think this is the first one: http://en.numista.com/catalogue/pieces38886.html

This seller may be cheap and quick, but doesn't seem to know much about his "Chinese" coins.

#1: Is not actually Chinese, but is from old Vietnam. It is a 7 cash (or 7 van, also spelled 7 phan) piece, from the reign of the Nguyen emperor Gia Long (reigned 1802-1820). You can see several examples on this zeno.ru page.

#2: China, from the reign of the Qian Long emperor (1736-1795), Board of Works mint. Extremely common - and with that damage, NOT "high grade". Zeno.ru example.

#3: I can't ID this one right now; given the combination of crudeness of script and thick border, I suspect it too is Vietnamese.

#4: Here we have a coin that actually does qualify as "old", "Chinese" and "high grade". It's a Song Dynasty cash, from emperor Zhezong during his Yuan You era (AD 1086-1094). Song Dynasty coins were often produced in "pairs" or "sets", with the same legend written in different scripts or fonts. Your coin is similar to this one, which is written in "grass script", a very fluid, ink-like writing style.

Genuine cast cash coins in iron zinc and lead can be elusive. They can be a worthy addition to any cash coin collection.
Just be beware of fakes.

We can't tell just from the pic. Genuine coins from this legend date from the Chinese rebel Wu Sangui in 1678. His coins are fairly scarce, by comparison with typical Chinese cash coins. The zeno.ru page for them only lists 20 coins, compared to the hundreds of types listed for the mainstream Qing emperors.

Wu Sangui ruled an area in the south of China, near the Vietnam border. As such, his coins found their way into Vietnam where they were copied by the locals. This list of Vietnamese copies of Chinese coins indicates Wu Sangui's coins were being copied in Vietnam not long after the rebel died.

As I said, the wide rims on your piece make me think it might a Vietnamese copy, but being a rebel, his quality control may not have been very good. This one, for example, looks very close to yours and is considered genuine. The best way to discern the difference is by weight: Vietnamese copies are always lightweight, often under 2 grams, almost always under 3 grams. There's even a class of Vietnamese counterfeit known as "floaters", because they're so light they float on water. Genuine Wu Sangui coins ought to weigh over 3.5 grams.

#3 is Yuan Yu Tong Pao, N. Sung Dyn. Running script variety. Worth about $1.

JCM meant "#4", not "#3". Coin #3 is like the ones linked to in my previous post.