Enable WordPress registration.

Its already in AnsPress. When you mention someone a notification will be triggered for that user. But currently AnsPress does not show name suggestion.

Default reputation cannot be deleted.

Make sure that new page is selected in AnsPress option. Save AnsPress option once. Also remove old ask menu link from menu and re-add it.

This is fixed now. Please confirm.

Fixed it. Please update.

Marvelous theme!

I have recently fixed issue with breadcrumbs, you can download fixed version from here: https://github.com/anspress/anspress/archive/master.zip