I am using the filebackup module for the first time, it works great and I'm impressed

Here are a couple observations if you don't mind:
First, I get this error when saving preferences:
Invalid path to tar utilities tar (GNU tar) 1.15.1
Preferences are set like this:
Path: /bin
Backup params: -cpzvf
Restore params: --directory / -xpzf
Here's the mystery (to me anyway) -- the module seems to work just fine, even when it 'fails' on saving preferences. Is there something I am misunderstanding about the preferences?
Second, here are some musings on features that might be nice to have.
1. Ability to declare exclusions, maybe by file extension/wildcard, by directory, or both.
2. Ability to set new paths and config items on restore, for a case where you are copying a site to start a new one at a new domain. This isn't thought through on my part. Perhaps this is related to the question about editing the config.php 'from the backend'? Maybe RonnyK could chime in?
3. Links to the .tgz files, but WITH protection unless you're a logged-in admin.
Last thing: could you explain about this please?
Thanks!If you think to leave backup files in directory you can add .htaccess file for download control.