Few question related to collections, data not working and how to define custom template

I am using Local installation Latest Ghost V3.1.1.
OS is Windows 10

This is my routes.yaml file


    permalink: /example/{slug}/
    template: example
    filter: tag:example
    data: tag.example
    permalink: /{slug}/
    template: index

  tag: /tag/{slug}/
  author: /author/{slug}/

Using this routes.yaml file posts with the tag examle being listed at http://localhost:2368/example/using theexample.hbs` template file. At this point everything is OK and as intended.

But my problem is when I visit a post from this custom collection the post is rendered using the default post.hbs template.
I want to use a custom template file for the full post of this custom collection.

I know there is a work around I can define a custom template by prefixing custom to that template file name like this custom-example.hbs But in this case I have to select it each time I create a new post for the custom collection.

I was wandering that may be there is a easy way to define it in routes.yaml file for once to used by all post in a collection.

EDIT Another question: Collection do not showing the meta title of the tag from the data instead it only showing the site tile similar to home. It should show Development - Example But showing Development (Page 1) Please see the image.