Hello @gnexman,
Please find the response to your query below in points:
Query #1, #2:
Response: It requires code customization so our suggestion to you is hire a professional developer.
To hire a developer please refer to below given link:
http://wensolutions.com/hire-wordpress-customizer
Query #3:
Response: The slider will adjust its height according to the image height. So whatever height you require, upload the image of that height. Also, make sure to upload the image of uniform height that you have chosen to display in the slider.
Query #4:
Response: You can display the Instagram in the widget area only in case of post/page using the widget WS Instagram Widget from the addon plugin which is recommended by the theme.
Addons plugin:
https://wordpress.org/plugins/ws-theme-addons/
If you want to show the instagram in content area of page/post then you can considere hiring the professional developer.
Hope this helps.
Best Regards!!