do I need a male and female for nanking cherries? And what soil type do they require?
Nanking cherries do need a pollinator. They are often planted in groups or as a hedge since they are like shrubs. They prefer moist, well-drained soils but can tolerate dry soils. Cherry trees are low feeders so make sure you don't over fertilize. Have your soil tested and add what is missing (N-P-K) before you plant. That may be all you need. In subsequent years if the fruit load begins to lessen, you can lightly fertilize with a low nitrogen fertilizer such as 5-10-10.
https://www.gardeningknowhow.com/edible/fruits/cherry/cherry-tree-care.htm
https://www.gardeningknowhow.com/ornamental/shrubs/bush-cherry/nanking-bush-cherry-care.htm
I have 3 beautiful nanking cherry bushes. They blossomed vigorously and when I checked for fruit I found that there were a significant number of dead twigs.
Nanking cherries are not usually bothered by pests and disease, so at this point, I would just prune out the dead wood. If you see any other worrisome symptoms check these articles for possible problems:
https://extension.wsu.edu/chelan-douglas/agriculture/treefruit/horticulture/cherryverticilliumwilt/
https://www.gardeningknowhow.com/ornamental/shrubs/bush-cherry/nanking-bush-cherry-care.htm
https://www.gardeningknowhow.com/edible/fruits/cherry/cherry-tree-diseases.htm