Can I put documents (downloaded on my computer) on a flash drive and bring it in to print out instead of first printing out on my printer and then making copies?

I believe so, the only thing I would do is call to make sure the printing services are working, sometimes it's down or there will be a wait time.

You print from a flash drive, but it's easier to email the document to staples "at" printme.com and use the access code you'll receive in reply to print without a device. No chance of leaving your drive behind that way.

Yes

I do beleive they provide that service