backup root partition
 

Can you backup / partition simply by using tar+zip, and later just unpack it if needed?
/home is on separate partition, but /boot isn't.

You can, but you should omit directories that are not needed or created on the fly from the system, like /tmp, /proc, /dev and /sys.

Or simply do it from a liveCD, and such issues become largely moot.

I prefer to take a snapshot, and back that up at my leisure.