Button / video / related post directory theme

Hi, i am pretty new with this, Have some questions, you can help me out.

I tried to use related posts plugin (not for listings) for the posts and pages, but this caused bug, site was not working properly. Is there any know plugin that works great?

The button, i read how to add a button, but not how to edit text in the button and and certain link. How can i do this?

For videos i used embed plus, the video is seen in the post but its not working on smartphone. Do i need to have specific plugin for this?

Hope someone can help me out.
Thanks.