Re: tar -czf taking long long time
You will need to unpack the tarball in a 'backup' directory and then rsync that with your 'normal' directory.
To speed up your tar.
You could also remove the z flag from your tar to speed things up, you could then compress once the tar is complete. Some files such as photos. movies and some data sets don't compress much anyway and as such the compression is just a waste of time. You can compare the tar size with the compressed size to determine its viability.
rsync is the best option in my opinion, then would be tar + incremental backups.