Expired domain names is a great game to play. I recently acquired 2 domain names listed in paid yahoo category for Tshirts and combined for about 20 visitors a day, and they would receive more if I actually built a website for them. I'm working on my own domain parking pages.
As for acquiring the domain names. From personal experience I wouldn't worry about pending delete domain names as much until you get a good foot hold of using back ordering systems.
Presonally to check the "popularity" of a domain name, I follow 2 steps.
1). I check out
http://www.alexa.com/data/details/tr.../www.spuzz.com
2). and I also do a text search in google, I wrap the domain name in quotes for the search. (ie. "spuzz.com").
These methods aren't perfect and 100% but no method is 100% and they work for me.
I follow a different process for finding domain names expiring. Normally people check for expiring domain names and check their popularity. I do the opposite, to some degree.
I built software that once I feed it a yahoo category. It will spit out the expiring status of every .net and .com in that category. That way I know it has a yahoo listing. I'm thinking about altering the software to check dmoz categories also.