Hello, have a look at "Improved target weight optimization in phenix.refine" article here: http://www.phenix-online.org/newsletter/ and, make sure you are using the latest version of PHENIX - this is essential: http://www.phenix-online.org/download/nightly_builds.cgi
I wanted to know what parameters should I use for subsequent refinement.
Which parameters do you mean? Optimal weights are determined per refinement run. It is not given that in a next refinement run the optimal weights will be the same as in previous one. Since weights optimization takes a long time to run (if you have multiple cpu machine then it can be run in parallel), normally you run it towards the end of refinement and not all the way through.
I would like to know what Fix X-ray/stereochemistry weight and Fix X-ray/ADP weights are for?
In case you have your own weight values, you can specify them and then phenix.refine will use them as is. Pavel