Flattening Layers PDF

I am using CorelDraw to write a Print-on-Demand paperback book (containing text with vector drawings) (350-400 pages), then will convert it to PDF using CorelDraw Export feature. The book has no transparencies. Never created any layer in any page of CorelDraw.

I need to use Master Page of CorelDraw, as it will make job very easy for auto page numbering, book title, any header, any footer. But then I was thinking , isn’t the same as now each page has 2 layers, one its own default layer and one layer of Master Page. So do I need to worry about flattening each page in CorelDraw?

I need this info as the book will have 350-400 pages, also I have never done any flattening.

Off course, first I contacted Print-on-Demand Publisher, they were unable to say anything about using these softwares (CorelDraw, Acrobat), all they can tell their requirements include that the book should be in PDF format, and in PDF file flatten all layers into a single.

Then I contacted CorelDraw, they were too unable to help, as that's something that Adobe can explain, like all layers are already in single form now in PDF or not etc.

So I am here now. Any help, guidance will be highly appreciated.