Theme development

Hello, Can anyone tell me how to create a list of taxonomy terms in homepage. I'm coming from WordPress background so I have no idea how to do that. I have my homepage as mytheme/templates/page--front.html.twig

I have created a new region called home_content in my theme.info.yml and I have created a view(block) for getting the taxonomy terms, added it to region in back-end and display it as {{page.home_content}}. It works but I have few questions.

I have an entity type with a field called "field_deadline" of type Date, where "Render as a regular field" is set to True. I need to set its format programmatically. I tried the following pieces of code that are ignored:

function hook_date_popup_process_alter(&$element, &$form_state, $context) {
  $element['#date_format'] = 'F j, Y';
}

Also, in a template function as follows:

i insert {{dump(items)}} to pager.html.twig to debug twig,then open product list page,turn page from first page to last page,some page can't display pager . and the debug dump 'items' print 'null'.why?

thanks very much.

on this page
https://www.drupal.org/docs/7/api/theme-api/overview

the 2 code samples at the top show 2 different ways to use theme api

in the second one the name of the theme being use (form, pager ect) appears twice
both as the name of the array ( $build['table'] ) and as one of the key value pairs stored by this array (array(
'#theme' => 'table', ..... );)

why is it necessary to mention the fact that it is a table twice?

I want use Panels for main page. And want to get slideshow and catalogmain were in the same row for screen wider 1100px. In Opera it is so/ But Mozilla places catalogmain under slideshow. For structuring i use float. I am new in sitebuilding so can not understand my mistake/ Please help/
na-poluostrove.ru

Hi, I'm using Bootstrap (no additional theme) essentially in my top navigation I just want there to be three things: the logo, the main navigation, and another navigation for external links. However, I don't want the external links navbar to be a part of the first navbar because I don't need any emphasis on it. Instead, I want it in a collapsible menu that can be toggled using the "three dash button". When the site gets resized, I want the first navigation to join the external links in the collapsible menu. How can I do this?