Hi again Paul,
If you want to sell a book in 2009, it is pretty much an expectation that you have a website at a bare minimum. The Internet is where people go to find out about just about everything now. A few browse through Amazon or a bookstore, but more find what they want via the web first, or at least look to see what they can find out about you/the book if someone recommends it.
It is just as important that you own your own site. For example, if by chance the publisher goes out of business, is slow to do maintenance, that's a really bad place to be. In addition, having a url (web address) like "www.yourbook.freebiesite.com" is generally considered less than professional since buying a domain is $10 a year and hosting can be as little as $8/$10 a month. The site doesn't have to be super fancy with a lot of bells and whistles to start, and you may be able to get up and running for just a few hundred dollars.
With regard to fulfillment, it all depends on where you think you'll send your customers. If you're mainly going to link them to Amazon, fulfillment is taken care of. If you'd rather sell direct from your site (because you'll make more money) you might need help with fulfillment but probably not for a while unless you really do a big launch and start selling tons of copies a week to the point where you can't handle it. A nice problem to have, but not always realistic at the start.
Hope that helps point you in the right direction.