Well, once you have a room full of long boxes, you kinda have to either become rich enough to build a new house with dedicated comic storage, or you start looking at digital.
Half joke aside (because good luck affording a house nowadays), reading comics digitally is actually very nice, but being able to have and store an entire published history of a comic on a single drive instead of taking up multiple boxes is too damn nice to ignore. And that's assuming you're paying for the digital version. If you pirate, the money issue is a major decrease in resources needed to enjoy comics. Hard to pirate physical copies of the very old and rare stuff, but easy to find digitally.
No clue. I read on a $20 tablet I got off Amazon. With the app that suits you, why not indeed? It's a total POS for anything but reading, but I bought it for an epub reader.