If you have questions about using mojoPortal, you can post them here.
You may want to first review our site administration documentation to see if your question is answered there.
How it is possible in blog module to add multi "Content Authors" so every author only can edit his own posts?
Sorry but right now is not possible.
Is in the list of improvements for the blog module, please review the road map http://www.mojoportal.com/roadmap.aspx
I need that feature,
and is it possible that new posts from author's posts to be waiting for verification by blog admins?
All features you mentioned are on blog road map , bug there is not a fixed date to doing those.