If you are in USA, I would create a legal entity in Delaware for example and go on with the crowdfunding campaign. For what i know Amazon is doing some kind of pretesting and during that just spread the word to some great book groups or go flyering to NYC libraries.

Engage your leads and create momentum for your book. you could also do some website and performing some A/B testing in order to understand what the customer is looking with some help of some SEO. After you get an impression and you go crowdfunding. Taxes dependes if you are doing the earning for yourselves or on a funded entity. You can just sell you book though Amazon and file on your earning afterwards :)