How does one who has not yet been published get editors to even just look at the work, or better yet, how does one go about acquiring an agent?

First, just to be clear, that information is referring to books, not short stories. If you're interested in books, you should learn all you can about that stuff. It means a lot.

(I think it helps to write and publish a few short stories along the way, myself. At the very least, it shows an agent and editor you have the ability to write something worthy of being published in some form.)

Yes, it seems most book publishers prefer to look at a book an agent is representing. This acts as kind of a pre-filter. It trims some of the slush off the top of the pile, since agents aren't going to send them manuscripts written entirely in pink crayons.

To get an agent, well I'm not the expert on that. My understanding is to have certain things ready: a partial (about 20 pages of written story), a one-page synopsis, an outline, a short summary (usually used in Query Letters.)

Then you send agents a short query letter, which is essentially asking asking them to take a look at your book idea and consider publishing it.

If they like what is in the query letter, they will ask for something more: usually one of the above things I mentioned. They may even ask for the whole book, but my understanding is it's rare?

Then they may ask for something else, and so forth. Eventually, they'll either send you form rejection letter, start ignoring you, or offer to represent your book--trying to get an editor to buy it for a few pennies or something. (Please excuse the cynicism )

That's my completely amateur take on how it works. I'm sure others will have better information--which makes me wonder why I'm writing this instead of working on my Work In Progress...

Oh, yeah--because I had a question that relates!

How much should a writer have prepared and polished before they start seeking an agent? Do they need the whole book written and polished, or just written, or just a few chapters, or.... ?

Open submission -- just send it it.

Agent submission -- your agent must send it it.

Solicited submission -- which means you must first send a query letter to the publisher telling them about your work and asking if they'd like to see it. If they do, they'll let you know.

I suspect there are different kinds of query letters, and that each publisher and agent have their own guidelines.

Short stories are a horse of a different color. Write them, finish them, get a couple people to look at them, revise as necessary, then submit them to magazines. You won't need an agent for shorts, and don't spend your whole life agonizing over one story. Finish it, send it out, move on.

If you are interested in learning more about submitting books to agents, I highly highly recommend reading some agent blogs. Chock full of useful information.

The best agent blog was Miss Snark's. She has now retired, but her archives are still available and well worth browsing through. misssnark.blogspot.com

Current blogs that are great are Kristen Nelson's, at pubrants.blogspot.com and Nathan Bransford's, at nathanbransford.blogspot.com