The Like Box is this:
https://developers.facebook.com/docs...-box-for-pages
You create a Facebook Page, maybe update it every time you post a new blog post, want to advertise a new book, etc, and those updates show up on people's Facebook feeds and they can like/share/comment from there.
Newsletters are definitely a lot more successful than the RSS feeds, but you also want to focus on social media. If you find it overwhelming to post something and remember to post it to Facebook, there are multiple services that will do the work for you - Check the RSS feed for updates every hour or so, and then post when you do add something.