The main issue with something like this is that by the time a book has been out for a couple of months, it's likely to contain out of date information, and instructions that can't be followed because ebay's changed or moved something.
If it was something like an ebook, it would require constant updating and even the most diligent and dedicated author will eventually give up, I'd say.
You're better off finding a blog, vlog, social media group or forum dedicated to selling on eBay - from what I've seen, the first two don't tend to be particularly technically-focused, though you'll find eBay tutorials for very specific functions (some osolete, some not) on YouTube, but mostly they tend to be more theoretical, motivational, "storytime", opinion / rants, with the occasional vague sourcing tip thrown in.
Community-based resources like social media groups and forums tend to be much like this one is... Someone posts a query, hopefully someone else can answer it..... and with theory, "storytime", opinion / rants and lots of vague references thrown in.
Peronsally, when it comes to account functions, I like to click on everything to see where it goes or what it does, if it looks like it will change something about how my store or account works, then I look for a "more info" link. With many functions, it's less getting the account to work to the best of its ability, and more finding out what settings there are, and then deciding which options best suit your business.
