Has Dongjiao Wholesale Market merged with Xinfadi? What is the closest subway station to Xinfadi?

No, most of stores of Dongjiao Wholesale Market move to wholesale maket in Tongzhou District. And some stores move to Shuangqiao (Xinfadi) Wholesale Market.

As for Xinfadi Market, the nearest metro station is Xihongmen Station. The distance is about 1.3 miles. You can find many stores that sell kitchenware products.