Let's go through that again, nacho. DON'T bind it! The agent or editor will want the pages loose, but held together with a rubber band. Rubber bands come in a variety of sizes. Some are big enough to wrap around a whole filing cabinet, so don't worry that the book will be too big for one. (And if it's too big for a rubber band, it will DEFINITELY be too big for a comb binder. You'd be hard pressed to find a comb larger than 4", and that probably won't hold a double spaced manuscript of a large book.
There should only be two in your heirarchy.
Agent
Publisher
The editor works FOR the publisher. Whether you should send it to one versus the other is the longest standing question in writer-dom. An agent might be able to get you a better deal with a publisher, should know and have worked with publishers (so has a foot in the door) and can help you understand any contract you might sign.
A publisher is often happy to work with you individually (depending on the house. Some only accept agented submissions, which might turn into an issue depending on your genre.) The editor is who you submit to AT the publisher.
Does that make sense?