The second half of your question is easier than the first, all you'll need is a linux rescue disk, once you boot off of that you can mount any drive you need to... Most Distribution disks have a "linux rescue" option at boot, so instead of just hitting enter to go into installation mode, type "linux rescue" and hit enter, it will provide you with some tools to fix, and recover data.
To do the first portion of your question check out unison:
It's a fantastic file synchronizer. I user it personally to synchronize my files to a windows file share which is in our data center and backed up nightly. So, combine unison with a cron job and a bash script that runs every hour or so, but only backs up once a day, and you're set... It's a fairly straight forward program. The other option of course is a simple cron tar job which tars and zips the specified files at a specified time...