Does anyone use buddypress?

As I said earlier your issue is related with PHP memory limit. please consult with your hosting provider for increasing memory limit. Also we cannot help solving issue without error log. I suggest you to post this question on BuddyPress support site.

Can’t install BuddyPress

It’s not memory I have enough

[BUG] Notifications in this site go to 404 if question was renamed.

Fixed.

How Can I Show Recent Questions In A Page By Shortcodes?

There is not any shortcode for that but you can use questions widget. There is an option to show question by newest date.

Limit number of notifications in the notification bar toggle

Override user/dropdown-notification.php from your theme and then use break After 5 loop.

How can I show how many questions?

You can use this function for getting total published questions: ap_total_published_questions() For counting users, you can try this: $result = count_users(); foreach($result['avail_roles'] as $role => $count){ if( 'ap_participant' == $role ) echo $count; }

I need facebook share social buttons after each question

I tried WordPress Social Sharing Plugin – Sassy Social Share and it is evenbetter with the mobile interface as it doesn’t use external server to redirect to the sharing app or page

Improve the Categories widget in the sidebar?

Yes you are right, its already in our task list. And you can expect this fix in next update. We will add a dropdown similar to GitHub which provide input field to search in dropdown.