How do I set up a mining script to implement my own buy and sell wash trading?
I'm not sure I understand. Do you want to do something different than the exchange-mine.py script included with the CredaCash software?
If the setting is not correct, will I lose BCH or CredaCash due to the exchange rate that matches other participants? If I want to achieve mining by buying and selling myself, do I need to set the same custom and unique market exchange rate for the "maximum exchange rate" and "minimum exchange rate"?
It is possible that the mining script will sell all of your CredaCash or BCH, if another user is using the exchange to buy or sell CredaCash. For this reason, the mining script allows you to set the minimum and maximum rates for trading on the exchange. Then if your mining requests match another user and result in a net buy or net sell, the net buy or net sell will occur within that range. Note you can also set an amount limit and trade frequency in the mining configuration file, so any trading will happen over time.