Well, the perm checker tells you what to update; so the proper chmods of those files/folders:
Folders - 777 (full read, write, execute)
Files - 666 (full read, write)
By default they're uploaded as:
Folders - 755
Files - 644
As for removing the preview reply, this can be done through the template editor; I believe there area few discussions over how IE handles AJAX on this forum, likely just use the search utility to locate them.
