Don't worry about this. We live to answer questions here.
Facebook limits the visibility of posts from business pages. This means when someone "likes" your author page, they don't see every post you make. Boosting a post is basically buying exposure: they'll show it to more of your subscribers, and you can target people who don't subscribe to your page, too.
In short: you're buying an ad.
I don't belong to any FB groups, but there are
lots of good groups in the world (including the Water Cooler). No harm in belonging to more than one.
It's more like people expect to be able to find these things. And I don't think you need a blog, per se, just a landing page with information about your published work and links to where to buy them. If blogging isn't your thing, there's no point in forcing it; it'll show.