As for putting your post in the wrong topic, don't worry about it. I only mentioned it for future posts. (Maybe a kind moderator will move this to a more appropriate place.) I agree that a lot of forums can be difficult to find your way around at first. They seem to evolve to make it easy for experienced users to do things but sometimes forget about new users. If anyone else reading this is a little confused as to how to post their questions you can find quite a lot of help via the "Help" menu (on the left-hand side of every Scribus forum page, near the top, under the Scribus logo). The links will take you to the Simple Machines Wiki where everything should be explained. (Simple Machines are the makers of the Scribus Forum software.)
Back to your original question...
Given the requirements you've listed, I think you just need to import your existing pages into a new document.
If you create a new double-sided document you can use menu "Page -> Import". You'll be asked which document to import from, which pages to import, and where - in this new document - you want to import the pages into (which, if you're going in chapter order, would normally be at the end.)
Once you have imported all of the chapters you can start to rearrange pages if necessary using menu "Windows -> Arrange Pages". Or you can create Master Pages to make page numbering easier (see
https://wiki.scribus.net/canvas/Working_with_Master_Pages ).
Once all of the chapters have been imported the new document will contain all of the text and vector graphics you have used but the image frames will be linked to the original images. Because of the way Scribus uses images, you shouldn't move or remove the original images as the document doesn't "contain" the images, it just maintains a link to them.
When you have all of the text in the same document you might want to think about using Styles to more easily apply consistent formatting (the first part of this thread post
http://forums.scribus.net/index.php/topic,1728.msg7717.html#msg7717 gives a quick overview of what sort of thing is possible, or better still, if you have the Scribus Manual loaded you can go to "Documentation / Scribus Basics / Working with Styles" for a much better explanation).
If you have any more questions, or I've not explained myself very well, then just say so.