Questions for those who only want to do digital purchase

So if I decide to purchase a book, but I only want to do a digital purchase. So after I do the payment, it'll automatically unlock my ability to view that specific book once I go back to that specific book and that will be it?

Unlocks forever and when they release the download, the same.

Yeah, it will unlock the book and grant access immediately. Sometimes it will take a minute or two, but it should be instant.