Can I access my domain address with or without the "www"?
Yes, you will be able to access the domain address with or without the "www" in front of the domain name.
The exception is a subdomain. If you host your domain with us, you can get to your site with or without the www. in front of your name. If you have a sub domain like this:
http://www.yourcompany.rdcsshosting.com , then you must use the www. in the domain name or it will not work.