First, change your document to facing 8.5 x 11 pages. You can lay them out in the order you would read them. Most printers will re-order the pages for printing themselves. If you are printing them yourself, some versions of InDesign have a "print booklet" function that will do this for you as it's printing.
Whenver you have a doument that is going to require two or more sheets of paper to hold all the pages it's crititical that you set up with facing pages of the final trim size of the document, so if your book is 8.5 x 11 and has 8 pages, set up as 8 pages 8.5 x 11 (facing pages) , NOT as 4 pages 17 x 11.
First of all, it's a lot easier to work, and you get to see what the reader will be seeing, and if any elements need to cross the spine for some reason it's a snap. Second, trying to impose on your own after you get beyond a couple of spreads is pretty prone to error, and third, unless youare printing yourself you never want an imposed file for the printer. It's his job to impose your file to fit his equipment, and if you try to do it for him it will cost extra for him to undo what you've done, if he can use the file at all.
If you are printing yourself (doesn't sound like it in this case), ID has rudimentary imposition capabilities suitable for desktop printers with File > Print Booklet...
Talk to the printer about the page count before you get too far. If it's going on press you'll need a multiple of 4 pages, and perhaps 8 or 16, depending on the size of the press. If the press handles this size in 16-page signatures, for example, it will probably be no more expensive to print 32 pages than 26 or even 24, and may actually be less since there will be less handling required in bindery. Going over what fits in a multiple of the signature size (36 pages instead of 32, for example) will cost a bundle in extra plates, setup, and handling.