[Note: I never used your platform I am referring to N810 with OS2008.]

Short answer: there is probably no easy way although I do know in OS2008 one can backup and restore settings this probably didn't exist in previous versions.

Long answers: Rsync should work, but it is slow over SSH (cryptography overhead) and even slower on small files (id.). Even more so on an embedded device.

You want to restore quickly all your config. Your config is mostly in /etc and ~/.* but also /var and /usr/local/etc and /root/.*

Your personal files are in ~/MyDocs and /root

Your installed application list is saved in /var. You get with $ dpkg -l command. IIRC this command also provides a way to export its installed applications so it can be imported later. Would not work immediately with 3rd party repositories. Those get backed up if you back up /etc and should be first to be restored.

As you can see, it already gets pretty complex. So instead of aiming for everything aim for some specific, important goals. State them here and we can help you backing these up.