[gentoo-user] rsync backup system

[Grant]

I just finished an rsync backup system that works like this:

Each of 4 Gentoo systems contains a folder called "backup" which
contains symlinks to local files and folders for backup.  2 of the
systems contain a folder called "sync" which contains the contents of
the "backup" folder for each of the 4 systems.  3 of the systems rsync
with one of the "sync" systems, and that system rsyncs with the other
"sync" system.

I've got a few questions for you guys about this.

1. I back up the entire /etc folder of each system, and some files
have read-only permissions.  This means I get "permission denied" when
I try to rsync them.  How would you handle this?

2. Some of the files I back up only allow root to read.  I can run
rsync as root on each system, but I don't allow root logins.  This
means in order to rsync the second "sync" system with the first "sync"
system, I must run the rsync command from the first "sync" system.
This means I have to run rsyncd on the second "sync" system in
addition to the first "sync" system.  I'd rather only run one instance
of rsyncd.  Can anyone think of another option?

3. The rsync process always completes with "rsync error: some
files/attrs were not transferred".  How can I get more information
about which files this pertains to?

4. Should I be comfortable running the entire sync operation every
night, or am I jeopardizing the longevity of my HDs?

5. If I end up with filesystem corruption on the SRC system, will that
corruption transfer over to the DST system during an rsync, or will
the transfer just fail?

6. Can I run rsyncd on a system facing the internet without fear?

- Grant