It is called "Reveal Commit".

With rebase, I would say, there would not have been a problem. Maybe it just is my limited understanding, but I don't see any reasonable use-case for merging into a feature branch.

You can configure external tools for that task. Please see https://docs.syntevo.com/SmartGit/Latest/Manual/GUI/Preferences/Tools

This dialog only should come up if the repository has been opened before.

Maybe the translation can be stored in Git notes.

Has been implemented, as Jeff wrote, years ago with the Investigate command.

I think, with 22.1 this default tool had been removed. Maybe you have it in this SmartGit instance because it was upgraded from an older version, or because this tool had been imported from the above website.

In the Standard window a Pull will update all unchanged local branches, so even with forced push there are no diverged branches any more after pulling.

Fast-forward merge is already done by Pull in the standard window. Reset Advanced is already available in the menu or as shortcut. The standard window follows the principle: often used commands should be easy to perform, less often used commands are a little bit harder - hence we want to avoid to fill the context menu with advanced commands.