Hi Jerry,
here is with what I can help.
On the first question, the problematic link: This is expected and happens because the user menu itself is just a CustomHTML webframe and some of the links are pointed to the "blog" application. If you manage it you can see the URLs start with {url: app-root $|$ blog}, which is a functional tag that will be substituted with the URL of the "blog" application root node. To change that you need simply to change the "blog" in the string, with the name of the proper application for that webframe - "cdreviews" in your case.
On the second question, users do not need to register more than once. In the scope of a single Integra installation, there is only one registration needed, but each blog application has its own members list.
A side note. From what i understand of your concept, I think we may need to build the user pages a little different, so they now reflect that there are three blog applications, not only one which is the template case.