Hello and welcome to allnurses and the legal nurse forum. You have certainly come to the right place for information regarding LNC's.
Check out the "sticky threads" (found at the top of this forum). They will answer a lot of your questions about educative entities, marketing tips, etc.
You mentioned the online course offered by the AALNC. It is a comprehensive course, however, one major drawback with it is that you have to be self-disciplined to get through the course. But you can work at your own pace, and it is far more economical than other options.
It sounds like you have an excellent clinical background to be an LNC. You already have valuable nursing skills. An LNC course will teach you how to use those skills to assist attorneys in medical-legal cases. You will also learn how to market yourself which is the key to a successful career as an LNC.
If you have specific questions, please post them here.