Mother of Pearl Series: Lunar and Transport

richardine

I am looking forward to exploring something about these beautiful series. I am only a beginner so it takes time to develop all the details about the necessary coins.

Please help me with the following questions:

What mint is responsible for their mintage? I've found some information concerning the New Zealand Mint, yet it is not clear enough whether it is really so or not.
Are there only two series presented and what the following minting steps in these ones can be? Hope they have something to show us in the nearest future.
Why the face value is fluctuating so noticeably from year to year (from 50 to 25$ for silver coins and from 1000 to 200$ for the gold ones)? It looks like 2015 was a crucial moment for the mint.
I've also some questions about quality and metal: it seems to me that the Lunar Dragon has no gold version, right? Moreover, apmex.com says the golden Lunar Snake and the golden Zeppelin coins are presented only in 'brilliant uncirculated' quality; is that true? See no point in changing their quality just for making an exception.

I am very grateful in advance.