Theme development

I know this is the core of D8 theming, but the documentation is really leaving me flat...

I read this page and, well... i ended up asking for help here :)
https://www.drupal.org/docs/8/theming/twig/twig-best-practices-preproces...

I copied /mytheme/templates/content/node.html.twig and made /node--view--nhp-news-slider.html.twig with some edits.
Now i want my slider to point to this new, edited node instead of the default.

I am currently trying to figure out how I can alter the markup of the Views Group By Title. I created a view that groups by a date field. The date field automatically becomes the Group By Title. I have been using the template_preprocess_views_view_field hook. Whenever I change the markup of the date field it changes it both in the title and in the view field as well. I want to just change the markup in the title.

I'm having trouble getthing the maintenance offline template to work. There's not a whole lot of documentation our there, but it seems like setting up a maintenance-page--offline.html.twig template should work.

I am specifying my maintenance theme in my settings. And the regular maintenance page works fine. But when the database is offline I just get a white screen with text.
$settings['maintenance_theme'] = 'xxxxxx';

Anyone else having issues with this? Or am I missing something.

Using the Flat Zymphonies theme for a one page site. Modules Void Menu used to set the menu links.
The menu links scroll to the top of each region as designed but I had to make the menu header a little taller and now the menu links scroll the page too far. I can't find the css used to control this scroll.
Any help is appreciated.

Hello I cannot find a way to theme http://morella.e-tck.com/node/11 page paragraph image (field_quote_image) the 3 blue rectengular images. The images that I want them to add class "img-circle"

Im having a problem in the business theme. Theme is responsive but images not responsive. I use d8. Please help me