About the first concern, you should worry and stress yourself out, writing takes time and patience, accompanied with mistakes, we arent perfect, and I’m sure several readers here will help you out with feedback and point out typos, errors and alike.
About the second well…
I think you should pace yourself, that’s a very rash decision and that turn on red lights to some people and to be honest, that can arise several misconceptions about what you’re trying to accomplish, good luck out there with your book, cheers.