Modification of the admin panel and technical support of the site on yii2

Something to fix, something to add to the admin panel on the site https://artonica.ru/
Learn more:

1. in the admin panel, the ability to select projects to display on the main page does not work correctly - not all projects fall into the drop-down list, from which you need to select http://joxi.ru/n2YMEy1sk1L852

2. add to the editing of the Project the functionality of inserting video from YouTube / Vimeo
http://joxi.ru/VrwDjKwToGlzZm

3. Customize the display of video screensavers in the mobile version.
Now in the mobile version, the output of only photos and GIFs is configured.
video formats are not displayed.
here is a screenshot of what the block of adding video/photo looks like
http://joxi.ru/LmGK96lIBNd9dm

4. Understand and give recommendations (and then apparently do) on the revision of the block of adding images and videos in general
Not all video formats are displayed in all possible browsers, because of this, several formats are loaded and all this affects (?) the speed of loading pages.
now the site has been loading for quite a long time and kind of because of the "heavy" pictures or GIFs.

The site, in principle, needs regular technical support, there are tasks to repair or screw new functionality, so we are looking for a specialist who will solve current problems and will continue to support the site