1) why are images produced under the microscope reversed & inverted?

Question

2) why does a specimen need to be centered in the field of view on low power before going to high power?

Answer 1

1. I know this is a poor answer but it's the best I can do. The images are reversed and inverted because that's what lenses do.

2. At high power it takes VERY LITTLE movement to take the specimen out of the field of view; therefore, you want to get it centered and you do that with low power and you have a relatively large field of view.