See here for purchasing a domain mapping upgrade and mapping from you free hosted WordPress.com blog to a domain name you already own. See:
For what is included in a bundle see here:
You can set up email subscriptions by using this guide > http://en.support.wordpress.com/widgets/follow-blog-widget/
If you would like a follow button to appear on the bottom right hand corner of your site for those who do not have WordPress.com accounts see here >
Find Friends Who Use WordPress > http://en.blog.wordpress.com/2012/05/01/find-friends/
You can customize the contact form with multiple fields, change the email address where you'll be notified, and mark feedbacks as spam from your dashboard. http://en.support.wordpress.com/contact-form/
See also Inviting Contributors, Followers, and Viewers http://en.support.wordpress.com/adding-users/
Note: As a spammer prevention you are limited to sending out 10 invitations at one point in time.
There is no newsletter function. See here for a workaround http://onecoolsitebloggingtips.com/2010/10/07/wordpress-com-newsletter-subscriptions/ The content of the second "newsletter"blog can be any content your wish to include in the newsletter. The second blog can have it's own follow blog widget for newsletter subscribers. You can create a custom menu on your main blog and include a custom link to your newsletter blog in it.