Mylar might be a bit more popular than ReadEra. We know about 1 link to it since March 2021 and only 1 link to ReadEra. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
I can answer question 1. To read downloaded fanfiction, or any other pdf/epub, you need a reader app. I personaly use the free version of ReadEra because it's the best I've found in terms of range of file formats, general functionality, and ease of use. I like it enough that I plan to spring the $10 for the paid version eventually. Source: 12 months ago
If you are looking for something specific to comics I recommend Mylar. Source: about 3 years ago
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