Ryuk would probably just be amused. He is a Shinigami who has seen a lot in his existence. Fanfiction is just another strange human creation to him. He might chuckle at some of the more outlandish ideas in the fanfictions, like a character having superpowers beyond the Death Note.
Misa would likely be excited. She is a big fan of Light and the whole 'Kira' concept. In fanfiction, if there are scenarios where she has more power or a closer relationship with Light, she would be all for it. However, she might also get jealous if there are other female characters getting too close to Light in the fanfictions.
There are several places. Fanfiction.net is a popular website where you can find a large amount of Death Note fanfiction. Archive of Our Own (AO3) is also a great option. It has a well - organized tagging system which makes it easy to search for specific types of Death Note fanfiction, whether it's about certain characters or particular plotlines. Another place could be Wattpad, though the quality and variety might be a bit different compared to the other two.
Some libraries also have collections of manga. You could visit your local library and see if they have Death Note. Another option is to look for digital libraries or apps that offer manga rentals or subscriptions.
Oh, for sure! Death Note is considered a masterpiece in the manga world. Its unique concept and the way it unfolds make it a must-read. The characters' development and the moral dilemmas presented make it stand out from the crowd.