If you haven't worked with Redux, it's highly recommended (possibly indispensable!) to read through the (amazing) official documentation and/or watch this free video tutorial series.
See above! As minimal as Redux is, the challenge it addresses - app state management - is a complex topic that is too involved to properly discuss here.
There are a few reasons why we use redux, the biggest being that it is widely regarded as the current best Flux implementation in terms of architecture, support and documentation.
You may feel differently! This is completely OK :)
Below are a few reasons you might want to remove it:
You're under no obligation to use Redux or any other Flux library! The complexity of your application will determine the point at which you need to introduce it.
Here are a couple of great resources for taking a minimal approach:
See above.