Hi there,
I understand that you encountered multiple errors which we will address for sure, but kindly consider that bumping to the thread without getting an answer from our side will slow down the reply process as the system resets the queue and it goes to the end of the waiting list.
Regarding the color of the text. If you are using the new text element you will need to go to the color settings and remove the default color from there. At the time being new elements do not get color from the theme unless you delete the default black color from the color field:

There is a feature request indicating this which one of our other customers asked to have that color picker no color by default which will get info from the theme options. I also added this thread to the feature request.
Regarding the error of the Cornerstone, I added a new page called Test Page, and added a template from the 30 Top … page called 30 Template. Then added the template to the test page and it worked fine. This shows that the problem resides outside of the Cornerstone.
Kindly check for the third party plugin conflict possibility by deactivating all of them except Cornerstone and check the case. If it fixes the issue for the page kindly reactivate them one by one to find which one is responsible.
Also, I suggest that you go to the Test Page settings in WordPress (Not Cornerstone) and try to add the settings with the same way the 30 Top … page has. See if in a step the conflict gets back to have more information.
I suggest that you for each case you open up a separate thread so we can tackle the exact case individually to be able to give you more specific and better suggestions.
Thank you for your patience and cooperation.