Hello,
I have run couple of years online business and used indiegogo and kickstarter platforms for presales.
I also write on Amazon kindle for e-books on marketing topics. Presently, I am a MBA lecturer who works full time teaching marketing. I would recommend you to do the following:
1) Use Amazon kindle keep a campaign to test,you can also register for free book campaign launch.This way you would have a start.Scale up by using salesforce free license for 30 days to generate and engage your leads,referrals update all of them at one place.
If you need more info on how to schedule tasks and increase productivity and to answer all your questions regarding business of e-books please hit me up,we could discuss over the call.
I am confident you will have a good productive call with me.

Regards,
Abhilekh

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 :)