I have done this for copying users from one system to another.
I copied passwd file deleted the non-system users from the copy of the /etc/passwd file, then tar it up. Also, copy the /etc/group file to ensure all groups are supported on the new system.
Then tar /home -cvf <tapedev>. Then copy the tar balls to the new system append the users portion of the passwd file I copied and untarred the users' home dirs in the /home dir or appropriate sub-dir under /home.
I am not sure how to do the rest of your question. If they are simply config files, I would tar them as well and copy.
CAVEAT!!!!!
However, you will need to make sure user groups are also present and make sure that all user permissions and ownership are the same when you tar them up. I don't think I had any problem with this on my system.
Hope this helps.
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