rsync as a bakcup tool and the case of rotated logs

[Louis-David Mitterrand]

Hello,

I use rsync (among many other things) as an incremental backup tool.
Every night I save /{home,etc,var} from several servers. On one of them
we keep 52 weeks of system logs, so each time syslog is rotated all old
syslog.x.gz (where x is between 1 and 213) change names. This impacts
our backup transfers because the incremental snapshot now has to include
all syslog.x.gz files even though only one of them has been added (and
one deleted). 

Now I am a very happy and grateful user of rsync. I was just wondering
if there is any way to:

1) have rsync "understand" that file names might have changed, maybe by
comparing files through their md5 signature instead of by their name,
that way rsync would see that /backup/syslog.198.gz is the same as
/var/log/syslog.197.gz and not retransfer it,

2) create hard-links to identical files in
--backup-dir=/backup/incremental-2002-11-27 when is detects that
/server/sylog.138.gz is the actually the same as
/backup/current/syslog.137.gz,

Thanks in advance for your insight,

-- 
    PHEDRE: Elle s'en est punie, et fuyant mon courroux,
            A cherché dans les flots un supplice trop doux.
                                          (Phèdre, J-B Racine, acte 5, scène 7)