No freight train connection to the factory??
There is. In fact it's called a "land port" for a reason, the park has a huge freight yard connected to 2 rail lines it's just not shown in this picture because it's shared infrastructure of the industrial park.
I don't think there is any railway link to the site, at least in the short term. Both of the two rail lines nearby are passanger only high speed (250 km/h to 350 km/h) lines (references: https://zh.wikipedia.org/zh-cn/%E9%83%91%E9%98%9C%E9%AB%98%E... , https://zh.wikipedia.org/zh-cn/%E9%83%91%E6%B8%9D%E9%AB%98%E... ). The train yard ~5 km north of the factory is 郑州南动车所, also a high speed rail depot.
That area is called 郑州港区 (literal translation Zhengzhou "port area", full name: 郑州航空港经济综合实验区) is actually for it's closeness to the airport (ZHCC). English reference: https://en.wikipedia.org/wiki/Zhengzhou_Airport_Economy_Zone .
Yeah I think so. Zhengzhou has perhaps the largest yard in China. The factory is there for a reason.
Toggle the layer to "Map" and you can find the railway lines easily, although train in the depot looks like a high speed train (huge, long windscreen).
All that track connected to the depot you are talking about is high speed passenger infrastructure. Just touching the south side of the factory is what looks like an old single track line if you follow it to the west there's a passing loop just the other side of the nearest village. If you switch to back and forth between map view and satellite view this eventually leads to a spur shown in map view that stops at a road. Not sure if the line is under construction or decommissioned or what.
I'm uncertain what to look for, since there's this "land port" which refers to high speed passenger and freight trains being brought together.