All of our themes are SEO friendly. When using backlinks to your website, the link will point to homepage only.
With default homepage slider you can’t use YouTube video. If you want to use YouTube video in homepage slider, you can use Cyclone Slider 2 WordPress plugin
Just install this plugin and create slider
Then Go to Appearance » Theme Options » Homepage Slider
Enter your slider shortcode which is provided by plugin without php tag
Please check the documentation