An effective thesis cannot be answered with a simple "yes" or "no." A thesis is not a topic; nor is it a fact; nor is it an opinion. "Reasons for the fall of communism" is a topic. "Communism collapsed in Eastern Europe" is a fact known by educated people. "The fall of communism is the best thing that ever happened in Europe" is an opinion. (Superlatives like "the best" almost always lead to trouble. It's impossible to weigh every "thing" that ever happened in Europe. And what about the fall of Hitler? Couldn't that be "the best thing"?)
A good thesis has two parts. It should tell what you plan to argue, and it should "telegraph" how you plan to argue—that is, what particular support for your claim is going where in your essay.
From Harvard College Writing Center, Developing a Thesis
Why create an outline? There are many reasons; but in general, it may be helpful to create an outline when you want to show the hierarchical relationship or logical ordering of information. For research papers, an outline may help you keep track of large amounts of information. For creative writing, an outline may help organize the various plot threads and help keep track of character traits. Many people find that organizing an oral report or presentation in outline form helps them speak more effectively in front of a crowd.
From Purdue OWL, How to Outline