Yes, Printer setup on openSUSE is still a clusterfuck, for reasons. You're best off in openSUSE KDE to just point your webbrowser at http://localhost:631 and log directly into CUPS and setup your printers that way.
If you want all your web video and whatnot to work, you need to install the codecs from Packman, in their entirety, or use a flatpak'd web browser. openSUSE won't ship patent encumbered codecs from the official repositories.
Unless you really know what you're doing, with Leap, or Tumbleweed, stick with the OSS and non-OSS repos provided. They are the ones that have been through the openQA process, and are officially "supported". If you enable a bunch of home:devel: or other repositories, just assume that they're unstable, and use at your own risk. If you're looking at a repository on OBS, and don't see openSUSE_Tumbleweed as one of the build targets, then forcing the install with a Leap or SLE package, may, or may not break things.
Regarding zypper ref and autorefresh, I can't recall exactly, but there is the chance that just running zypper dup and hoping that it refreshes everything on it's own, with non-standard repositories may fail, which can lead to some weird edgecases.
Just in general, you're going to want to run zypper ref && zypper dup (not the other way round) As far as YaST being targetted more at Leap than Tumbleweed, you're exactly right. And there's a reason that we don't ship it with newer flavours of the distribution.