@Seven.of.nine, I still suggest not to start learning git at the command line (due to aforementioned reasons, which you confirmed to be justified), but to create a GitHub account and to utilise git solely via GitHub’s web-frontend.
Technically @smatkovi is correct, that the first action would be to “fork” (in GitHub’s parlance, i.e. “clone” in bare git parlance) @ichthyosaurus’ sailfish-patch source code repository.
None. You are thinking of package repositories, which usually provide RPM files or Debian packages.
IT people usually do not care about concise wording, everything is quite fuzzy, the pinnacle is the term “system”.
In this context “repo” means “git source code repository” at GitHub.
Sorry, there is no way around successfully creating a GitHub account for this task becoming feasible for you.