Thanks @aiplusfinance for stopping by. I noticed that some like me do not know how to post in the communities they belong. SO i made this post. On the issues raised:
a. Yes, i partly believe that since communities are united by passion and interest, it will be easy to deal with any spammers together. Then again, If there are community founders and moderators, and whitelisting is possible, then I believe the admin should be responsible for allowing or not allowing certain individuals to post.

b. Yes, definitely, we should be allowed to belong to several communities. We have more than one hobby or interest.

c. Using real names that represent the communities is the sensible thing to do.