Sandra (Thistle Cove Farm):
First, congratulations on interesting a publisher - any publisher -in your book!This puts you way ahead of the majority of writers out there.
How do you know if this one is the right publisher for you? You don't, until you ask questions to find out. You have to know what you want out of a publishing deal....lots of money? Just getting your material out there? Lots of marketing exposure, so your future publications will have a built-in audience?
Decide your needs, then ask this publisher and any others who express interest where they stand on your pertinent issues.
You don't need an agent, particularly if you've already made contact with an interested publisher. A good attorney can handle the contract details for you (which should include details about how the publisher will market your book, because if it isn't well marketed, it won't sell.
You've asked a question that takes a book to answer and fortunately I have such a book. In Write Market & Publish Your Book (www.acappela.com/books.htm) I cover everything from query letters to marketing and choosing a publisher. It might save you time to read it before you sign a publishing deal.
Again, congratulations and good luck!