Cannot tell you how durable Cordura is but it is used in just about every textile jacket out there (at least the decent ones). From looking at the Cordura website it appears there are different types for different uses so I dunno if all motorcycle apparel uses the same type.
The 500 denier part is the thickness of the thread used to stitch it together. The bigger the number the better. 500 is the most common size though some jackets use 1000 and I’ve even seen 300 on some.