The beauty of using WordPress as the base platform for your ecommerce website is the ability to quickly and easily install lots of great plugins provided free by the wordpress community.
The WordPress plugins page can be found here: http://wordpress.org/extend/plugins/
1. Stop Comment, Login and Registration Spam
Adds CAPTCHA anti-spam methods to WordPress on the forms for comments, registration, lost password, login, or all. For WP, WPMU, and BuddyPress.
2. WordPress Email Plugin
This plugin will allow to to change the default WORDPRESS FROM sender to your own.