SBS 2011 Essentials does not have remote web access (RWA) set up by default. You will ideally need to set this up (and get an SSL cert, i would recommend against a self signed one for ease of use) which will allow you to securely tunnel (via SSL) to pc's/server using remote desktop. Your other option is to use something like Logmein or Teamviewer to accomplish this.
RWA requires you to have some form of domain name pointing to the server's internet IP as well. This can be done via dynamic dns just fine. You will also need to open port 443 (https) to the server on any firewall's.
RWA is really nice, though it may not be the easiest to set up. I have not used anything short of SBS Standard so I dont really know how to get this set up other than a quick google search.http://titlerequired.com/2011/07/15/set ... ls-part-1/http://titlerequired.com/2011/07/15/set ... ls-part-2/
Cant speak for how accurate the above links are, like I said, I have never used essentials.