No. Sarah J. Maas put in a great deal of effort to create the Throne of Glass series. She developed a detailed and immersive world filled with magic, political intrigue, and adventure. The story has its own mythology, history, and set of rules. Fanfiction, on the other hand, is usually based on an existing work and modifies or expands on it. Throne of Glass is an original creation and not a fanfiction.
It depends. In some cases, the creation of certain types of glass art or products might draw inspiration from elements found in comics. But not all glass is directly based on comics. It could just be a matter of coincidence or a shared aesthetic.