I do it WITH www, mainly for tracking purposes because I use subdomains as well....but you could go either way, whatever suits you
most people use www.domain.com when visiting a site. why break tradition? using www. now will only make it easier later.
I use also www in one of my sites and no www in the second. Maybe some experts here can tell us what is the significance of that change in searches....if there is any
Hey use 301 redirect...It will help you in SEO of your site. redirect www to non-www or vice-versa. Here is an article about this concern: http://www.webconfs.com/how-to-redirect-a-webpage.php
every people who are willing to click your ads will always use www to search site as they are still not familiar with other so use www i prefer this in the sense of earning money
either way is fine, but once you started in a way don't change it search engines still see a diference from www.site.com and http://site.com or http://site.com/index.html ...
Whichever way you do is fine as long as you : 1. stick to it throughout your campaign 2. (and this is even more important) 301 the one you decided you rather not use to the one you use. in this case, whatever you (or others) link to you with, ends up giving links to the same domain and you won't create duplicate content.
funny thing i did a link compaign and i got pr = 0 for www. and pr= 3 for non www. but the compaign was www. so it's crazy
I agree .. be consistent. I made the mistake one time used both at the same time. When I finally learned enough about SEO, I couldn't do much about it on a Windows based hosting account. Good luck.