Hi there!
I'd like to place a bid on your work specified.
We can clarify the specs, but basically we can script all the directories / sql dumps / svn dumps etc to your hard drive, and then assist with getting it running again on your secondary system.
The best way to check if all necessary files are backed up, is by trying to get it to run on a second system. After all, if the primary system fails there is no other way to know if you backup strategy is sound by restoring to a second machine :)
The script can be done using bash, rsync, mysqldump (if using mysql), or pg_dump (if using postgres). We can even automate it using cron (eg, once a week), and only do it if your external is plugged in.
Let me know if you have any further questions.
Thanks
Mark