I currently have a Ubuntu Server 7.0.4 server that I have Subversion setup on. How do I backup the subversion respository so I can reimport it later if needed. What I just did is copy the repository directory from /var/svn to my NAS, is that good enough?

Also, I'm thinking about reinstalling my server with the latest version of Ubuntu Server, and re-setup everything so it is more secure than it is now. How I have it setup now was hacked together just to get it to work locally...but I think I want to be able to make it so I can access my subversion from the outside. Are there any guides/tips on how to keep the server secure from outside attacks?

Our SVN repository at my current employer I take monthly fulls, differentials and daily incrementals of just the directory in case o data loss.