In the US, many public universities allow access to the public, including use of computer terminals that will allow access to paid databases. In many cases, you could bring in a usb stick and save copies of articles downloaded from such databases, or at worst you could pay a small fee to print some stuff out. AFAIK, that kind of access varies state by state though, so you need to call university libraries near you to find out.
Yes, you can use it fully offline.
To back it up I believe you’d just need to backup your
.pass
and.gnupg
directories.I haven’t used keepass, but the entry from the archwiki should give you a good idea of usage, and it also lists some helper apps: https://wiki.archlinux.org/title/Pass