When you make FTP backup does it only create backup of user's accounts or does it include some of other dirs like /etc ?

thank you

It only makes backups of site files including the MySQL DB . Everything else would usually not change and can be replaced. You would have to backup those manually if you need.

ermm so if I create FTP backup and HD crashes I will not be able to restore all data needed from the FTP Backup?

You should be able to get back your client's data. Like I say, for the rest of the files, you could backup on your own as they do not change that often. Your clients' data are what may change which you cannot recover without the backups.