You have been given answers to your questions as stated, I'm just curious about what it is that you want/need to do? It could be that you are trying to extract some information that is special to your company or some such, but if you are looking to extract normal website statistics, then maybe you shouldn't roll your own. Instead look at programs such as Analog which is highly configurable, and free.
in reply to parse gzipped weblogs
Just thought I'd mention it, in case that might be a simpler and faster solution. Parsing and crossreferencing weblogs is no fun task, and the logs tend to be quite big pretty fast so it is also an intensive labour for the program. Of course it is possible (and as such, easier than in most languages) to do in Perl, but it might not be the best tool for the job. :)
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It is pitch black. You are likely to be eaten by a grue.