Menu link to the most recent article with a certain taxonomy term
For your first question:

As your are displaying "Teaser" view of the node in your view, so you are getting two title of the node. If you want to hide the "Title" of the node and display the override title, then you can follow the below step.


Go to Administration -> Structure -> Views
Edit your views "latest"
Click on "Content" in "Show" setion under "Format" section of your views, it will display the popup. 
Select "Fields" from form which is opened in popup and save the form.
Now, you will see "Title" and "Body" in your "Fields" section. 
You can remove the "Title" from views or Edit "Title" fields and check "Exclude from display" check-box, so it will not display in views.


For Question 2:

If you want to append latest node title with path (latest), then I do not think, there is solution for this. 

But, if you install "pathauto" module, then you can create url alias for the same or you can append term name with view path and can get term id for the term name.