I got a bus + sleeper from the Gold Coast to Sydney last year, loved it. Bed was fine, was cool having my own little cabin. The shower was adequate, kinda cramped but the temperature was good. Breakfast was proper food, unlike someone else's description of the Syd-Mel. The electricity was a bit weak as I recall, just made my laptop drain a bit slower.
Going in the other direction during the day was absolutely lovely, a much nicer experience than flying. Got to see so much scenery and felt very relaxed...until the bus ride.
It was not much cheaper than flying and I only did it because I care about carbon emissions. Would be nice for the environment if they could bring the cost down - when NSW did free trips they included the XPTs and they were booked out, so people are obviously willing to use them if the price is low enough.
Or just carbon tax the fuck out of air travel 😈
For downloading, I use Readarr or manually download from where I buy the books. A lot of the time the books I buy have DRM so I end up pirating them anyway 🤷. When readarr sends a book to calibre, it tells it to convert it so I've always got epub and mobi available.
For accessing my library, I use calibre-server, which I think comes bundled with the calibre desktop app. It's got a basic web interface for uploading, editing some metadata, and downloading; and an OPDS API which my e-reader can use to download books. If I'm outside my home network I use my VPN to access it because I don't trust calibre to be secure enough for internet exposure lol.
Don't recall why I chose this instead of calibre-web but it works fine for my purposes. I don't read comics though.