Adding customizer options Twenty Sixteen

Hi All,

I would love to build a theme that others can use.
I am trying to extend the Twenty Sixteen theme with a couple of extra’s. I am getting stuck and could use some help. I need to add the following to the Theme options panel/customizer.
These are the options that I want users to be able to adjust within the customizer options panel:

In the navigation bar users can change:
? Font type selection
? Font size, type
General Fonts users can change:
? Font type selection of <P> and all <h>
? Font size, type and line height
Social media:
? Enable social media icons and entering the url’s.
? Select position, header or / and footer

As an extra it would be awesome if there could be a welcome message. I have seen this in other templates. I also saw this in the WordPress update yesterday. They even had video in there. How is something like that done?

Welcome to theme page
? A standard page which will load once the theme is activated. Here you find resources, documentation and FAQ for example.

I am going wrong with the java scripting.I added options and it did not show up in the customizer. I just do not know what to do where sometimes. Please advise. Working pieces of code that I can “paste into” the Twenty Sixteen theme would be greatly appreciated.

Kind Regards,
Mike