At first i am very sorry for my bad english.i am not a english guy.
some suggestion for new q2a update:
1) home page infinity loader like qoura.
2) After registration user can follow tag/category and specific people.
3)In home page user only see questions and answers from his followed tag/category and people. Like facebook we only see post from our liked page/friends and followed people in news feed.
4)q2a message system is very complicated.need some improvments in message system.
6) user can request other user to answer their question. requested people get notification.
5)Advanced notification system
user get notification
* when new question will asked from their followed tag/category (admin can limit the notification number)
*when users questions/answer/comment will hidden by moderator.this is very important beacuse some time user confused why they lost their points.
*when their question/answers upvoted and downvoted
*when their question get new comment and answer.
*when new message arrive
i think this suggestion can make q2a more advance.