Tachiyomi could be the one for you. It's customizable and supports multiple sources for manga. However, keep in mind that the availability of apps might vary depending on your region.
Well, there are a few ways. One option is to look for websites that have mobile-friendly interfaces and offer free manga. But be careful as some might not be legal or safe. Another way is to check out apps that have a free section or limited-time free offers.
One way is to find manga apps that have an offline reading feature. For example, MangaZone often offers this option. Make sure to download the manga within the app when you have a good internet connection, and then you can read it offline. Also, check if the app has settings for saving manga locally.
I wouldn't recommend looking for free manga reading on Android as it often involves copyright infringement. Instead, consider subscribing to legitimate manga platforms that offer a wide range of content at reasonable prices.