2. Was it first discovered by a chinese dynasty and if so,

The earliest known texts that we can reliably call references to gunpowder are Chinese, and are Tang Dynasty. The earliest recipes that have survived are Song Dynasty, and these are most certainly gunpowder. It's possible, likely even, that the earliest versions of gunpowder would burn, but not quickly enough to be useful for guns or explosives.

As far as we can tell, the Chinese invention of gunpowder was an accidental discovery in the course of alchemical search for immortality. The Chinese name, huoyao 火藥, can be translated into English as "fire drug" or "fire medicine".

For lots on the early Chinese history of gunpowder, including translations of primary sources, see Joseph Needham and Ho Ping-Yü, Science and Civilisation in China: Volume 5, Chemistry and Chemical Technology, Part 7, Military Technology: The Gunpowder Epic, Cambridge University Press, 1987.

3. was it brought to the west by marco polo.

Gunpowder appears to have spread to the West via the Mongol invasions. There are early possible mentions of gunpowder weapons being used by the Mongols in the West (in the Middle East) in the 1270s, and possible use by the Saracens against Crusaders at the siege of Acre in 1291 (however, these might just refer to the use of burning projectiles thrown by mechanical artillery). The earliest certain descriptions of gunpowder in Europe are by Roger Bacon, in 1267, where he describes fireworks. His knowledge of gunpowder and fireworks might have come from William's of Rubruck's visit to the Mongols in the 1250s. This predates Marco Polo's return, so knowledge of gunpowder didn't come to the West through Marco Polo.

Somewhat later, in the 14th century, we have unambiguous descriptions of gunpowder weapons in use. Whether such weapons reached the West in the 14th century or the 13th, they appear to have been important in spreading knowledge of gunpowder in the West - note that the very name "gunpowder" describes its use in guns.

1. If the discovery of the chemical compound of gunpowder emerged anywhere else independently.

There have been claims that gunpowder was independently discovered elsewhere. Some of these claims are rather far-fetched, such as ancient Indian gunpowder (e.g., 4th century BC). Brenda J. Buchanan, Gunpowder, Explosives and the State: A Technological History, Routledge, 2016, discusses the ancient Indian claims. Such claims are usually based more on extreme nationalism than evidence. The Indian evidence amounts to incendiaries having been used in ancient India, which might or might not have been similar to gunpowder.

There are also claims of independent Arab invention, either in Spain or the Middle East. The usual dates are not long before gunpowder would have reached the Arab world via the Mongols, and are largely based on later manuscripts that are claimed to be copies of older works. The accepted opinion is that gunpowder wasn't independently invented by the Arabs, but was brought by the Mongols.