I ordered a book through FIFO and then chose a second book off the members shelf via "choose more from this member." There was no action on either book (waiting for member) and I discovered my library had the first one it so I cancelled the first request.

I wanted the other book and it's not a the library so was waiting to see what happens. It never said "Printed" but it says "Will mail by 9-8" with the details under the i as "sender has until 9-10 to mail this book to you." Does this mean there has been some action on that end? I'll wait until the 10th but if nothing happens will my order for this book go to someone else since I didn't originally put it in through FIFO?

edited for weird typos!

Yeah, it means they accepted it.  They have until the 10th to mark it mailed.  If they miss the deadline, it will go to the first person in FIFO that has it.

Exactly! They accepted the request but have not printed any pacaging materials yet.