Thanks to everyone for your replies. Rid, I believe that I am misunderstanding the terms. I am under the impression that having taken the course, passed the NR test, that I am now a Certified EMT-B. Doesn't licensing come next when I actually start to practice in a particular state?
The National Registry is a national exam used to test and certify EMTs that they meet the minimum requirements.
Application is then made to the State for permission to work and perform as an EMT in your State.
Some states call it Certification and some License. Usually at the EMT level it is known by the State as Certification but I believe your state also refers to Paramedics as Certified also.
For some states that is semantics except for Texas which differentiates Certified and Licensed Paramedics by an Associates degree.
The reasons each state insists on certifying or licensing individuals are:
1) control over who is practicing in their State
2) funding by fees to maintain a State EMS agency as oversight.
Schools do not do background checks and just about anyone can get an EMT certificate by passing a course and taking a test. If you have been convicted of certain crimes such as being a child molestor or drug dealer, that State may not want you practicing as an EMT in their state regardless of your NR certificate. Once you are in the State's system, any illegal activity or professional violations of care that you commit, your employer will be obligated to report to the State. You can lose your State certification to practice in that state but your NR may not be affected. You could then apply with your NR certificate to a State like California which does not have, as of yet, strict oversight for its EMTs nor do they require background checks in all California counties.
As for as stopping on scene:
You are going to perform as a first-aider. You can use your knowledge/training for scene safety, to open an airway, stop bleeding and perform CPR. In some States, bystanders are allowed to ASSIST a patient to take their medications. Check with your local and State statutes for Good Samaritain laws. This may apply when you are not on duty also after you are officially certified by the State.