Anthony regarding the question about which is better a top bearing pattern bit or a bottom bearing flush trim bit the answer depends on what you are doing. In some cases one will work and the other won't and in some cases it doesn't matter which one. If you can clamp a template to either side of a form for example, it doesn't matter because if you mount it under you can use a flush trim and it you clamp it on top of your work you can use a pattern bit. Let's say that you can't rout deep enough while following the template. You can remove the template and a top bearing pattern bit will follow the profile that you have already completed so that you can go down the thickness of the template on the second pass. Are you starting to see the differences in the methods yet?
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.