Yes, there are. Project Gutenberg is a great free option. It has thousands of classic novels that are in the public domain. You can easily download and read them on your device.
One option could be Wattpad. It has a vast collection of novels in various genres, from romance to mystery. Another is Goodreads. Although it's mainly a review and recommendation site, it can also lead you to places where you can read novels. Also, Project Gutenberg offers many classic novels for free.
Well, legal manga apps usually have partnerships with publishers and follow copyright laws. However, there are a lot of shady apps out there that violate these laws and are definitely illegal.
In most cases, they aren't bad. But some poorly developed manga apps might have issues like battery drain, compatibility problems, or security vulnerabilities. So, it's important to choose well-known and reviewed apps.
There are a few. Tachiyomi and Crunchyroll Manga are worth checking out. Tachiyomi is known for its customization options, and Crunchyroll Manga offers simulpubs of ongoing series. It depends on your specific preferences though.