What are the best practices while enabling audit trail for work orders?

Summary:

We are enabling audit policies for common work execution in oracle fusion. We would want to know the following:

1. If there is any way to purge records in audit tables
2. Does enabling audit for a significantly long duration cause problems in environment performance? If yes, how can the performance be improved?
3. We are planning to enable only a few attributes under work order operation materials such as Required quantity, quantity per product. What are the best practices to ensure that the production environment doesn't face any slowdown due to audit trail?