Re: Advice for POD version
1) Although others seem not to have problems with IngramSpark covers, I did. It may be me.
Here's a place where it will provide you with the template needed to create the cover:
I don't have InDesign, but it does allow PDFs as well.
I use Killion publishing to create my covers and they provide with the template needed for upload for paperback covers.
2) I checked on the "author copies" at KDP and saw that the book must be "live" to get the copies without the resale banner. Might have been my problem. I wanted to check out the book before I published it.
3) I use B&N personal books to create my ARCs. Some organizations require a "marketing plan" as part of the review process. A friend who is traditionally published shared with me an example from one of her books. They can be slow sometimes, and I've used Lulu as well for these ARCs (check for a discount code, but still a bit higher than B&N).
4) Google "IngramSpark vs. KDP" and you'll find a lot of reasons for using both avenues. Basically, bookstores won't buy from KDP, but they will from IngramSpark, and IngramSpark has a wide reach there.
That's my experience.