svn update updates your working copy it doesn't do anything to the repository, so the answer to your first question is no. The answer to your second question is no as well, but not for the reason the question implies. svn help will show you all available svn commands, and svn help <command> will show you the help for specific commands. I'm not wanting to come off as talking down to you, and maybe you know this already, but your question suggests that you might not have much experience with svn.
in reply to Re^2: Track subversion changes
in thread Track subversion changes