how do I lay out two brochures side by side on the page to prepare for printing?

I'm creating some brochures to hand out on the street.

My plan is that the brochure will be a half page size (8.5 in x 5.5 in) laid out two to a page where each brochure will be printed in portrait orientation (8.5 in tall by 5.5 in wide). (I.e. the text will be sideways to the page if you view the whole page in portrait orientation). I want to print them at Fedex Office on colored paper and have them cut them in half by Fedex.

I laid out a flyer on a 8.5in tall by 5.5 in wide artboard and I'm happy with it. It includes text and two photographs, all in grayscale. (I'm saving money--B&W printing only, but on colored paper, probably blue.)

I'm new to illustrator and the next task will be a challenge: lay two flyers side by side and prepare for printing. I know I need to respect margins but not sure how large they are. I know I need to center each flyer in its half of the page and account for the printer margin on three sides of the flyer, while having the flyers look centered after the cut.

I also need to know if there are any extra steps to prepare for printing, and whether I should deliver them a PDF or AI file.