Almost 3 years ago since I posted this thread. Thank you for all the responses.

I believe Ted's description matches the configuration for my pool. The skimmer has 2 holes, one leading to the pump and the other leading to the main drain. And, I thought the saucer-looking thing that I found in the skimmer was a weight for the skimmer basket.

Recently, I was adding water through the skimmer when I noticed that some dirt around the main drain moved. That's what led me to realize that:
1. the second hole basically gets piped to the main drain (as clarified in http://wiki.answers.com/Q/Should_the...r_have_suction) and
2. the saucer-looking thing is a "skimmer diverter"

Anyways, just updating the thread in case there are others who may also be clueless as I've been and may benefit.