The answers to your questions in Q1 about latency percentiles and such can be found in the FAQ document at http://www.oracle.com/technetwork/database/nosqldb/learnmore/nosqldb-faq-518364.html .
The other parameters you are asked about are intended only for internal use, and so they are not documented. By default, these parameters are not visible to users. They become visible in help messages in the Admin CLI when you issue the command "hidden." Did you discover them in this way?
Latencies greater than this number of milliseconds are generally ignored.
This is a string of log property settings such as would appear on separate lines in a java.util.logging.config.file. Multiple assignments can appear on this line, separated by semicolons.
An example setting:
Changing this parameter causes the RepNode to be restarted.