About WP-Plugins.org Hosting
All of the data on wp-plugins.org is backed up several times a day and snapshots are made continuously, so your data is very safe.
You can read all about Trac, which powers this site, on TracGuide.
Subversion is an elegant version control system that is very easy to work with. If you're working on Windows there is an excellent shell integration plugin called TortoiseSVN that puts all the Subversion commands in your context (right-click) menu. There is a similar tool for Mac OS X called SC Plugin.