Disable comments

(copied from comment above, so that this question will get an answer): You can try http://wordpress.stackexchange.com/a/89238/26350 if you want to disable comments but still want to have the comment form visible. – birgire Oct 24 ’13 at 1:46

Restore trashed posts with comments

Once you restore the posts that are trashed you can try running the comment-fix.php script to reset the comments to appear and show the correct count. If it has been over thirty days in the trash the comments are gone for good, sorry.

stackexchange-like submit comment window

You can use WordPress’s built in TinyMCE editor anywhere in PHP code using wp_editor(). This would output all the necessary styles and scripts for it to load, and there are a lot of options documented in the codex link above.