How do I restrict the contributors permissions?

What I've done:

1. Modified the 'Wiki Settings' to only allow "edit wiki privileges" to Administrators and Editors.
2. Used the 'User Role Editor' plugin to allow Contributors to 'edit posts', but not 'edit other posts' or 'publish posts'.

The results:
1. The Contributor is still able to publish wiki posts, without prior editor review, using the front end 'Create New' tab.
2. The Contributor can use the front end and back end 'Edit' buttons to edit anyone else's wiki post, regardless of article setting.
3. When using the back-end, the Contributor must submit new posts for review.

How do I fix this so that regardless of whether accessing the wiki from the front end or the Admin panel, the Contributor must submit new posts for review, and can only edit their own posts?