Hello,
1) Because you set white bg + white color for the Dark buttons
Once I changed the color then everything is ok https://recordit.co/HvW0VKlEer
2) Create footer static block using Elementor or WPBakery builder (depending on which one you use as the main page builder on your site) to create 4 columns layouts (Static Blocks > create new ). Then go to Appearance > Widgets > add Static block widget to Footer widget area and choose the block that you just created.
Regards