I just went through all of this 2 months ago, however I didn't do it online. I live in San Diego so I went down to the Naval Medical Center in Balboa Park and visited the Tricare office. They did everything for me, all O really had to do was tell her my personal information (address, phone, etc.) and she filled out the rest. There was roughly a 30 day "processing period" for me inwhich I was enrolled but had not received my paperwork or card and was not able to schedule appointments, but I was still covered for ERs and stuff if I wanted to walk in. I also had to register with the hospital before scheduling an appointment, but that can be done same day as scheduling an appointment.
I haven't used dental, I have an awesome civ dentist that I still go see, but please post some info on the dental side if you get that far.