Acquia Cohesion renames to Site Studio from version 6.2. Tell me more.
You have to upload a JSON file to provide the index of the icons within your chosen icon font.
Opacity is set using a decimal where 0 is transparent, 0.5 is 50% and 1 is solid.
The Youtube video embed is responsive so it should expand to the width of its parent. If you do need to set a width you can apply the Width CSS property through the Style Builder.
The WYSIWYG (ckeditor) adds a paragraph tag around the text within the block quote. This causes it to inherit the text size of your paragraph base style.
Custom styles are CSS styles for classes.