Good list! I liked.....here are my views...
1. preview for post
This may be complex to implement like Wordpress but q2a should have similar to stackoverflow.
2. drafts post.
3. schedule post, post planning
I suggested these two features long back but they were not on high priority to implement. I also feel now they should be implemented.
4. surveys / polls
These are important for the qa site growth,
5. points for regular login (for example 1 for 24 hours)
This will encourage users to come back again and again.
6. Update for existing Noahy achievements plugin, to receive points when achievement unlocked, also ability to create new achievemnets !
are you talking about Badges plugin? it is easy to modify but this kind of plugin should go into q2a.
7. reactions plugin for posts - as facebook ability to post REACTION after read posts (with ability to add custom reactions - with images - too) :)
This is nice to have feature.
8. verified users badge - ability to mark from admin panel
I also suggested this long back, similar to twitter verified user.
9. hide categories / posts from MAIN/HOME page
I feel there should permissions for categories so that if admin want to discuss some things under certain category then they can do. some discussions can be hidden from regular users. similar to how they do in forums.
10. sort questions/answers/comments in moderation page/admin and filtering by categories showing in moderate section
agree, this one is required. If there are too much answers/comment then it should show 1,2,3 page no at bottom.
Quiz plugin: This is most important plugin for user engagement, they can show their expertise on topic of their interest, in return there should be reward badge. This can differentiate q2a from stackoverflow or quora.
I liked other suggested features also but above should be on priority.