Just one reason better retainability and wider content selection. Idk what tracker OP is talking about but most good trackers nowadays have a Bonus Points system that benefits long term seeders. Yeah the problem of people downloading new freeleech torrents and deleting thing right after they are clear of HnR is still a thing is most if not all trackers but the good ones don’t get affected much by it.

Yes there is. They’re called Kavita and Komga. If you wanna host Doujins then there is Lanraragi, it has a better tagging system then both of them but struggles with chapter merging and all.

Kavita is the preferred one nowadays.

Yes you can but the experience is not that good.