I'm a big fan of using whatever you're most comfortable with, but we've used lump exclusively in our WSM's for 5 or 6 years now, and if I really took the time to load it right, I can get 12-14 hours, but normally, I don't mind adding a little coal from time to time. I get 8-10 without too much effort most of the time. Kingsford is ok, but I notice whenever I cook with it I end up belching for hours afterward. The K competion briquttes seem to not cause that, but for what I can get an 18lb bag of Royal Oak lump for, and the results I get, I'm a lump fan.
And we almost exclusively cook on either a WSM or a Weber kettle
I like Bludog's method for the kettle. It's very similar to how the aftermarket Smoke-EZ unit works.