Concerning covers, one thing that I've been very careful about is my branding. Often on the old kboards, I would look at covers in people's sigs, and it was sometimes hard to get a grip on what they wrote.
So I chose to go with one of the more expensive routes--sticking with a single designer. We've had some enlightening email discussions concerning what makes a great cover generally and what specific steps we're taking with mine.
I've worked with Deranged Doctor Design in a variety of ways. I've painted covers and they added font. (Dragon Hoard, Stolen Legacy--in sig.)
I've sent them a mockup of a future painting, gotten feedback, and then painted the cover to fit the joint idea (Twelve Tales of Christmas).
And I've chosen stock art and they added font (The Golden Key, Bellerophon). The last happened after an epic painting fail on my part. I painted not one but two covers for Bellerophon, and they were both branding fails. One looked like a middle grade girl's book, and the other was MG boys'. (Aargh, aargh, aargh...)
It was really nice to have professional people to bounce all this stuff off of. For a font only cover, it costs only around $100. By the time you deal with all the Shutterstock licensing for doing it on your own with commercial licenses, I wouldn't have saved that much. Certainly not enough to justify the time expended.
OTOH, for Snow White and the Civil War I went ahead and hired them for the whole cover. It's not in my sig since it's not pubbed yet, but you can see it here:
https://absolutewrite.com/forums/sh...-Civil-War-cover-feedback-on-complete-duology. The good news is that I think these two are the best covers yet. The bad news is that covers like this can run $300 each, and it's hard to make that back in profit. What with the fixed costs of owning my own domain (twice), commercial email account, online classes that I wish I hadn't taken, and cover art, I'm still in the red.
Also, the wait time for DDD is in the neighborhood of 7-8 months. Pre-mades are nearly instant.
So, it's one of those choices. You can get cheaper covers by scouring the pre-made sites. It's much harder to achieve a consistently branded body of work, but you'll be able to actually turn a profit sooner. I haven't seen pre-mades for my genre that I like as much as mine, though--not even close.
OTOH, I write fantasy. It might be easier to find good ready-to-go covers for romance. I'd say it's worth scouring sites with pre-mades to see what kind of fit they are for you. Look not only for a single cover, but see if this solution will actually provide for a body of work. If that doesn't satisfy, then I'd check out a designer and start forming a relationship. Either way, the decision can come with a price tag--possible missed sales vs. paying down that credit card for your covers.
For formatting, I'm still kinda in limbo. I can't make Calibre work, at least not at my current frustration threshold. I tried Vellum (yes, you can use a non-Mac platform if you go through MacinCloud), but honestly, I preferred my own formatting for ebooks (Word files loaded onto KDP, Smashwords, and D2D).
Vellum is supposed to do terrific paperbacks, but I can't tell. A free demonstration version of Vellum is loaded onto MacinCloud, and that only does ebooks.
I'm really dreading going through the whole print book formatting experience again, though. I've done it straight on Word. It's a long, laborious process, and you've got to become conversant with terms like widows and orphans. The headers and footers alone are enough to make me consider ditching writing altogether and taking up a less demanding activity, like drinking.
I wasn't super impressed with the D2D paperback formatting, but I'm considering going that route. A lot of people like Vellum for that, too, but the program is $250, and like I said earlier, I'm already in the red. I don't think I can justify spending that much when I'm already in so deep for covers. Unless you do a lot of book fairs, very few of your sales will be paperback. And what if I'm as disappointed in the paperbacks as I was with the ebooks? Then I'll be even deeper in the red and no closer to a working system. Been there already with online classes, so I'm cautious.
Hope something here helps. : )