There are too many different questions asked both in the Secure Note and the last message that is really confusing. I suggest that you keep each additional question to a separate thread so that we can focus on each one without any confusion.
Let's have this thread only for the original question which was the problem you have imported the demo content. For the other questions please open up a separate thread for each question.
Now the problem of the demo import must be caused by the fact that you are using the latest version of the theme which is version 6.1.6 but an old version of the Cornerstone which should be updated. So please update the Cornerstone to version 3.1.6.
By the way, I tried to access your website but it is not working when I add /wp-admin at the end of the URL. If the problem of demo import is not fixed yet after the update you need to give the exact URL of the admin which we need to use.
Just a last warning that it is not recommended at all to add demo content in a website that you already worked on. The Demo content will erase all your settings in the theme options and will ruin whatever you have done n the website. The demo import feature is meant to be used for cases that you installed the theme and WordPress from scratch and now you want to have a starter.