Taro,
The idler pump is not one of the water pump bolts.

IIRC, the 11th bolt you are talking about is installed just to the right of the long gold bolt. See this pic:

bolt goes here

It remains empty until the fan pulley assembly is installed.

RE gaskets: Methylene chloride is your friend <img src="/forums/images/graemlins/smile.gif" alt="" /> <img src="/forums/images/graemlins/smile.gif" alt="" />... Get some NAPA gasket remover and apply it with a cotton swab. Use a copper scraper so you don't gouge the aluminum. To make a copper scraper, get a 5" section of 1/2" copper tubing. Press it in a vise or hammer on a clean, flat surface until one end is flattened. File the flat end until it resembles a chisel or scraper.

Ed