Does {abhorrent overlord} count towards his own devotion trigger?
Yes he does. So you have a minimum Black Devotion of 2.
Yes. Devotion triggers when the creature enters the battlefield, and so it counts itself. This is because it is on the battlefield when the trigger resolves. (That is, if no one killed it in response or something)
Someone please correct me if I am wrong or worded this in a confusing way.
Yep this all checks put. It is an ETB effect and therefore he has to be on the battlefield for it to trigger
Awesome, thanks guys and gals!