I am planning on launching a stackexchange web site and would like to better understand how to make it successful. (Initially, I thought that asking this question was equivalent to asking people to give up business secrets. But I realize now that when stackexchange launches the likelihood that two sites will compete with each other is close to nil. So we all benefit from sharing ideas on growing our sites so we can defend them against the big boys when they join the party.)
What are the key ingredients in making a stackexchange web site successful? Is doing paid advertising for the site important? Is having a big mailing list of potential participants important? Is SEO important?
I'm also interested in the importance of having a set of experts who are willing to answer questions as soon as the site launches. In answering this question, Adam Davis writes: "Jeff and Joel both agree that to start a really good SO style website, one must already be or have subject matter experts that are there to start it off."
How critical is this? If it is critical, what is the best way to gather a group of SMEs to answer questions on the launch date?