I can't for sure answer the second part of your question, but I'll see if I can help with the first.
In my virtual host section for each of my hosts, I have this for the logging:
CustomLog "| /usr/sbin/rotatelogs /var/log/httpd/website-access_log.%B 2629800" combined
The %B appends a month name, and the 2629800 is around the normal number of seconds for a month.
This gets me:
I use Analog to do stats and in the configuration file when I tell it what log to look at I can use a wildcard and tell it to look in "path/to/logs/website-access_log.*" and it will analyze all of the logs that match as if they were one big file. Again, not sure about webalizer or how it is configured.
Hope that helps (partially, maybe, at least).