If you do not want to have a social dialogue alongside your content, unchecking 'Enable Activity for Participants' will hide Activity in this zeeting.
Enabling "Keep posts private" means, only you as the presenter will see comments and questions from participants. If there is a particular post you would then like to make public, you can do so by selecting "Make public" next to that post. Once a post has been made public, it can not subsequently be made private again.
If you do not want participants of a zeeting to view other participants of that zeeting, unchecking 'Enable People for Participants' will hide People in this zeeting.
This section enables you to configure the way your live presentations work:
Firstly, you can decide if people that participate in your presentations are able to revisit your zeeting once your presentation is over. (Note, even if you give people ongoing access to your zeeting, you can always change your mind later by revoking their access on the Send screen.)
Secondly, you are able to set your zeeting such that when you present, your polls start off by displaying no votes (even if that poll had been voted on on a separate occasion). This is useful when you present the same zeeting multiple times or if you want to run a test presentation of a zeeting before your actual presentation and don't want your 'test votes' to impact the actual presentation.
A couple things to note - when you are not presenting, the poll/s will show the aggregate of all votes. Similarly, in the Responses section of Analytics, you will find the aggregate of all votes. By comparison, in the Presentations section of Analytics, you will find the votes cast during that particular presentation. This will allow you to compare poll responses across different groups of participants.
When you're not presenting, participants are notified via email of relevant activity happening in the zeeting such as new comments being posted. You are able to turn these notifications on and off in this section.