My b2evolution Version: Not Entered

Hello,
This is my first time here so hope I am posting these questions into the right place. Here goes with the questions and hope that someone can explain these steps to me in simple terms as I am not to experienced with this whole process but I am a fast learner:)

I want to be able to have multiple blogs to keep all my topics and articles seperate example: all health related topics one blog, all gardening topics yet another blog,

Now I want to allow others to comment with posts to these blogs, however I dont want to have any outside users creating blogs of there own to my site?

How can I achieve this process as I was going to go thru wordpress but while reading there topics there they suggested that b2evolution would work better to create a lot of blogs on different topics and link them altogether into say one large blogging circle if I am understanding and explaining this right.

I also want to be able to change my skins for each blog on there own so that it will reflect to the subject at hand again example: health topics, gardening topics etc. But also on the main Blog itself it will show all the other blogs and there topics that they each cover sort of like a index to all the other topics and there own blogs etc??

Is this simple to do and achieve using this blogging software?

And if so can someone here please be so kind as to in simple terms put the steps here to achieve what I am after please?

thank you so very much for the help with these questions and I welcome all feed back and suggestions as to how I should proceed with this software that seems to have so much more features with it then wordpress for what I am after to do and work with. I am still working my way thru the form reading and hunting for these answers as well but as of yet have not seen the topic answered or addressed as of yet which is why I have decided to post this topic here for some much needed help with my questions.
Thanks everyone.

libby