The number is how many people have rated that book.

Currently, there is no way to know your FIFO place for books you post, but you can guesstimate by adding the book to your reminder list before you add it to your shelf.  Your reminder list will tell you how many copies are in the system.  When you add it to your bookshelf, your place in FIFO should be whatever number was on the reminder list plus one.

They are how many reviews that the stars are based on.  To see the number of copies, you will need to put the book on your Riminder List (RL).

The numbers after the star rating show how many people have rated the book.  (If you hover over the number, an explanation pops up.) 

To see how many copie of each title are in the system,  add the book to your reminder list and then look at your RL, which will then show you how many copies of each book are available.

When you have a book posted, thre is no way to know where you are in the FIFO line except on the day you post it (by looking at the book on your RL.) 

Looks like a few of us were answering you at the same time!