In reply to:
Pardon my ignorance, but do these methods mean that should my router drop the connection and change my IP, people will be able to access the new one with the same URL?
Yes, the way that it works is that your PC (or some other device on your network) will contact DynDNS (or whoever you choose) periodically, and tell them what your current IP address is. DynDNS will update their name servers with the updated information, so people going to your URL will be directed to the correct IP address. On a PC, you will be running a small program which does this automatically - some cameras and other network devices that rely on DynDNS will have the software built in.