Implementation of niche blog

We are a legal Knowledgebase company desiring to create an income stream from those people searching for terms relating to divorce.

Our target users will search google for geographic specific keywords, like “Boise divorce lawyer” or “Georgia alimony laws.” They will not generally search for a national term like “divorce lawyers” because the returned items will not be specific to their location.

We intend to write regular blog posts for generic common divorce related topics. These will not be geographically specific. There will be 8-10 major topics (categories?) like Alimony, Child Support, and Divorce for Women, Divorce for Men, Mediation and so forth.

There are about 1,000 cities in America that are larger than 100,000 in population. With 10 major topics, this would work out to 10,000 categories (or tags, not sure which), requiring 10,000 regular posts, each with individual SEO and links… an overwhelming task.

We intend to monetize the program using a combination of Adsense and Banner Ads.

Is there a way to rank for a geographically specific long tail search term, like “Topeka divorce mediation” without having to have hundreds of separate websites, one for each major city and state?

We have been told that if we put all of the categories, tags and geographic keywords onto a single wordpress site, it will become so slow to load and respond that google will not show it.

So assuming that we need multiple websites, how do we do the following?

1. Set up a master website, with all the plugins, widgets, settings etc. and then easily clone it to our other subsidiary sites

2. Modify all the sites at once if a new widget or plug-in comes out we want to employ.

3. Manage our ad placement on a bulk basis. See metrics regarding overall site activity as well as individual site activity.

4. Create posts with unique content for each of the subsidiary sites. We own The Best Spinner, but have calculated that it would take way too much time to spin and post a daily blog to hundreds of our subsidiary websites.

Thanks in advance for your attention and advice.