We're preparing to launch a serious test of direct ebook sales and expect to develop answers to many of the questions raised by the OP and others. "Serious" means heavy advertising in Facebook, with clicks going to a custom landing page which is Woo Commerce enabled and delivers via Bookfunnel. (Hi, Julie!). I used Patty Jansen's approach as my model. (Thanks again to you, Patty, for this and for years of solid guidance in this forum.)
Before starting our new publishing company, I had ten years as an Amazon apparel merchant, and had concluded that Amazon will never be a reliable business partner. I was willing to publish with KDP, but quickly learned that introducing a new series the conventional way in Amazon was not likely to succeed economically.
I came to Indie publishing from a forty-year career in technology development and marketing, so I'm used to hearing lots of doubts and skeptical observations. I've never been offended since this kind of resistance is a very necessary part of the process of introducing a new way to do an old thing. The doubters force us to deal up front with "buyers' objections. In every new application design project I managed from the very first days of mainframes and online systems, the skeptics always made us think of better, simpler ways to do the job.
Julie's experience with her "CEO" is a case in point. In fact, Bookfunnel's decision to expand into direct sales support and integrate with Woo Commerce is what persuaded me to give this a determined try.
I won't attempt to convince any others to go this route, just give a nod to TwistedTales and the few who've pioneered it.
I will list a few of the things I've learned so far, however:
1 Volume is the problem to solve first, not after you've assembled all the pieces. To build a direct selling and customer support platform and then settle for a few hundred sales each month is an economic waste of time.
2 Go big or go home -- if your pilot effort earns out, be prepared to scale rapidly. Scaling is really hard, especially in Facebook ads. After sending the first two novels our series to the editors, I spent months poring over the accumulated wisdom of Facebook advertising consultants. This was in addition to taking Mark Dawson's course. I learned via reading and then my detailed emails from the best of them that they don't know that much about scaling, beyond increasing the ad spend. That won't work reliably or significantly or quickly with Facebook. Can you drive traffic to your content-rich landing pages with other ads? Or other traffic-gen tools like the excellent ones from UpViral? You need to know, and now. Solve how you'll do this before you invest in the several building blocks you'll need. Be ready to exploit launch success before you spend a single dollar on advertising.
3 Become an expert in landing pages. The folks at Instapage and its competitors know a very great deal, but their expertise is mainly in B2B marketing, not B2C, and certainly not in "converting" finicky readers. A successfully designed landing page will convert twice as many visitors to trying a free book or buying one as a slap-dash, copy-cat, template page will. Meaning doubling your direct sales revenues.
4 Limit your audience. Target a selected group of readers carefully and shape all your program around their needs and expectations. I agree with the several skeptics that many mass-market readers will not want to try this new channel. Forget them! Build a smarter, more demanding audience, especially those frustrated with Amazon's continuing decline in shopping quality and new book discovery.
5 If you have a new author name, or a new series with no branding, take even more care with your landing page and follow-up email campaigns. Selling a new series direct to readers means not just explaining the Woo + Bookfunnel delivery scheme, but engagingly presenting a new author and new main characters.
6 Given this doubled persuasion challenge, give your niche audience an entirely new experience. If they really want something, and cannot easily get it in the big stores, they'll be much readier to try the new delivery method. And make quality your lodestar: read-through will be the key success factor in selling series directly.
7 Read all of Patty Jansen's comments on this topic, and when you do, see particularly how she uses her method to capitalize on her boxed sets. In our case, we'll have the first three-novel series boxed and ready for sale by November.
8 Sales taxes are potentially a major concern if one intends to build a substantial sales channel. I've spent the better part of two weeks with reps at the two major services, Avalara and Taxjar, and have developed our strategy for handling tax filing if we succeed with our "stealth launch" phase. Mind, our books are written for a global target market, so we'll have issues both in the US and other countries.
I'll leave this topic for now with one, to me, all-important mantra: Facebook users are not looking for books; they're looking for entertainment. Engage their imagination and sense of humor, or curiosity, or dread, or mystery, or romance, and the selling will come naturally.
Best of luck to other wide authors and self-pubbers attempting to master this challenge.