few pre-sales questions

No problem for the questions. It's what we're here for, both before you purchase and after.

1 - does jfb connect works on jomsocial 3.2.0.5 on joomla 3.2 ?

Yup, we test extensively on JomSocial 3.2 and Joomla 3.2/3.3.

2 - with or without jfbconnect authentication, will all my users able to share activities stream?

I'm not sure what you mean here, actually. What activities stream? The social stream we show at the bottom of this page is being pulled from the SourceCoast's Facebook Page, Twitter Stream and LinkedIn Company pages. It's not a stream of all user activity. If you're talking about something else, just let me know.

3 - if Automatic Posting disabled, can we still post manually ? and how does it work?

Depends on the type of posting your talking about. JFBConnect supports a few ways to push content back to different social networks:
Open Graph Actions - These are 'actions' users take on your site, like uploading a photo into JomSocial or leaving a comment in other extensions, etc. These can be posted to the user's Facebook Timeline automatically when they perform the action.
Social Post - You can setup "Channels" that you want to be able to easily push content from your site to, like a Facebook Page or Group, Twitter Stream or LinkedIn Company Profile. From any page of your site, you, the admin, will have a "Create Post" button where you can add a quick comment and push the URL to any of those channels. Channels are what are also used to create the Social Stream at the bottom of this page.

4 - does jfb works with jomsocial events?

We don't have specific integration for JomSocial events yet. Any users that register through the social networks we support will be able to interact with any of your JS Events just like any other user on your site though. If there was specific integration you were looking for, let us know. We're always looking for feedback on what users are looking for.

Thanks,
Alex

No, JFBConnect won't do everything you're looking for for a few reasons.
First, all of the social networks require a unique URL for the content that's being shared. You wouldn't be able to share each individual post because JomSocial doesn't have a direct link to each activity post in the stream. Without that, the only thing that can be shared is the full stream URL itself.

Next, JFBConnect doesn't have an 'email' option. We do have sharing buttons for Pinterest, Twitter, Facebook, Google+, LinkedIn and others though.

I hope that helps explain,
Alex