" 

 :I wouldn't worry that much about a list of which countries are in the First World, although if you find reliable lists you can cite them. If they differ that's fine, as long as they are reliably cited. 
 :Same holds true for multiple definitions. You can select some that seem most reliable, cite them all, and use them as the basis for lead section of the article. 
 :If the term is recent, that's fine, you can discuss how it was developed post-WWII. You can also discuss briefly if similar terms were used earlier. 
 :If you decide you want to switch topics, you can do so, but I think you should be able to work on this one without much problems. | "