I don't know what you mean by resold. A book with an ISBN can be advertised for sale by any retailer. When one sells it's printed via POD and at the end of the month you get a royalty paid via Lulu. But often only if the amount = a minimum amount per site. So, those other places have not bought them, they are using your ISBN to advertising your book as being available (via POD.)
Oh, some pretend they have used books for sale, when often they are not used at all, and they have in fact got no copies at all.
So, does Lulu actually allow me to make a separate file for the title pages and such, and put the book in another file? Will they know to put them together in the same book? How would that work?
You can load separate files up for the pages. I forget the maximum limit, but read this. http://connect.lulu.com/en/discussion/31778?_ga=2.51291689.100400917.1541127821-2048438831.1541127821#toc-hId–905363151
It is not humans who create the books at Lulu. It's done by a Project Wizard that you upload file/s to. In the order that you want them in, and it stitches them together in to one pages PDF file.
They cost a lot of money ...
I took a look at Google Docs, and I am not sure if it will Save as the type of docx or PDF Lulu's Project Wizards will accept.
If you want a totally free MS Office 'clone,' take a look at this >> https://www.openoffice.org/
Thousands of people use it, so it's safe.