Editted Theme Files Get Updated/Reverted Every So Often

When you are using third party themes then always create the child theme for the third party theme because they always do changes and update the theme version so it will over write all your customization in your theme. You can get help how to create child theme here https://codex.wordpress.org/Child_Themes

Where is the stylesheet code?

The most common would be /wp-content/themes/your-theme-name/style.css but this may not be the case depending upon the theme you are using. The easiest way to find out is to use Chrome Developer Tools. In Chrome open your website and right click on the element you would like to alter the CSS for, then click ‘Inspect Element’. … Read more

Featured images are cropped on index and post page

This is likely a tweak the theme author made to make the images in the theme responsive or adaptive. You may want to look at adding “min-height” to your CSS and this should address your problem. https://css-tricks.com/almanac/properties/m/min-height/ Also another thing to note if you using “100%” anything the actual dimension is governed by the parent … Read more

Password Protected Page + Showing Different Page If Not Authenticated/Authorized

As ialocin mentioned some requirements will require extra customizations. I can create a number of passwords to access the page You would create user accounts. Passwords don’t exist without users. An expiration date can be set for each password This isn’t implemented in wordpress and requires the most work. You could probably store a date … Read more