Do you let the old URLs 404 or do you redirect them?

So after a year or two there would be thousands of 301 redirects - would you eventually delete these after a year or two?

For a real estate website, when a house is sold or taken off of the market. What should happen to the listing? 301 redirect it to the grouping (such as zip code or city) which that listing resides in? 404 it?

As an example from your site....are you concerned with for instance this duplicate content:

http://dailyfantasybaseball.org/category/daily-fantasy-baseball-picks/

http://dailyfantasybaseball.org/2012/06/27/june-27-2012/

I suggest you set WP to only show an excerpt of the content on pages that aren't the actual content page.

First, Google Analytics reporting does not, to my knowledge, influence SERP rankings. Altering the data collected through Google Analytics should not affect SEO indicators.

Second, this is from here: http://briancray.com/posts/time-on-site-bounce-rate-get-the-real-numbers-in-google-analytics/

Once this code is installed, your site will update Google Analytics every 10 seconds under the Event Category "Time", the Event Action "Log", and the Event Value will be based on the pattern of 0:10, 0:20, 0:30, 0:40, 0:50, 1:00, 1:10, etc.

The script does not change your bounce rate, it just gives you additional information.