It is really important to have the website as open and accessible as possible. Even options such as free logins or free accounts will prevent some users from continuing on into the site. Many users, especially with security issues are less likely to provide any type of personal information for fear of being spammed or have some type of security problem with their computer.
For any type of web site selling a product or service it is critical to have information on the site regarding actual business information and contact numbers. If business information including addresses and phone numbers change it is very important to immediately change the web based information as well. There are many consumers that will first make personal contact before making an online purchase so being available is important.