Hello, I got a few explanations for you.
Starting with your latest post, NUMBER OF THREADS WRITING TO DATABASE is a number of concurrent threads that are writing events to the database. The default value should be optimal, it can be tweaked to achieve better performance of saving events, but let's say it's more 'advanced' setting.
Reducing events and detections storing time will allow you to save some disk space, especially events storing time.
Unchecking storing filesystem events will stop recording of all file related events like write to file, file opened, etc. They will still be anal