If the house is built on Long Mai or indirectly receives the dragon spirit of Long Mai, will it have any impact on the family's fortune? ...

If you can get the spirit of Long Mai, you will definitely have good luck for yourself and your family. However, how can you be sure that it is Long Mai (I don't know which province or city you built it in, and many places have been destroyed). For example, the land is the largest mountain, and the gas of one mountain is a little. Mao Zedong's gas of the land is the gas of Long Mai, and so is Genghis Khan. This is also the category of geochronology mentioned by Chinese traditional culture.