As for 1. yea you download software from websites if it’s unavailable in your system repository, but most common software is available.
It’s like Microsoft Store or Google Play store, except everything is free (as in beer) and most of the time it works (it works, but bugs happen like everywhere else).
As a Fedora user that used to use Arch, yeah, wisdom comes from experience. Arch is not bad experience, I just kinda got tired of it.